I see that the site selling the material is based in California. You could politely ask them if they are familiar with California Penal Code 653h:
(a) Every person is guilty of a public offense punishable as
provided in subdivisions (b) and (c), who:
(1) Knowingly and willfully transfers or causes to be transferred
any sounds that have been recorded on a phonograph record, disc,
wire, tape, film or other article on which sounds are recorded, with
intent to sell or cause to be sold, or to use or cause to be used for
commercial advantage or private financial gain through public
performance, the article on which the sounds are so transferred,
without the consent of the owner.
(2) Transports for monetary or like consideration within this
state or causes to be transported within this state any such article
with the knowledge that the sounds thereon have been so transferred
without the consent of the owner.
(b) Any person who has been convicted of a violation of
subdivision (a), shall be punished by imprisonment in the county jail
not to exceed one year, by imprisonment in the state prison for two,
three, or five years, or by a fine not to exceed two hundred fifty
thousand dollars ($250,000), or by both, if the offense involves the
transfer or transportation, or conduct causing that transfer or
transportation, of not less than 1,000 of the articles described in
subdivision (a).
(c) Any person who has been convicted of any other violation of
subdivision (a) not described in subdivision (b), shall be punished
by imprisonment in the county jail not to exceed one year, or by a
fine of not more than twenty-five thousand dollars ($25,000), or by
both. A second or subsequent conviction under subdivision (a) not
described in subdivision (b) shall be punished by imprisonment in the
state prison or by a fine not to exceed one hundred thousand dollars
($100,000), or by both.
(d) Every person who offers for sale or resale, or sells or
resells, or causes the sale or resale, or rents, or possesses for
these purposes, any article described in subdivision (a) with
knowledge that the sounds thereon have been so transferred without
the consent of the owner is guilty of a public offense.
(1) A violation of subdivision (d) involving not less than 100 of
those articles shall be punishable by imprisonment in a county jail
not to exceed one year or by a fine not to exceed ten thousand
dollars ($10,000), or by both. A second or subsequent conviction for
the conduct described in this paragraph shall be punishable by
imprisonment in the county jail not to exceed one year or in the
state prison, or by a fine not to exceed twenty-five thousand dollars
($25,000), or by both.
(2) A person who has been convicted of any violation of this
subdivision not described in paragraph (1) shall be punished by
imprisonment in the county jail not to exceed six months or by a fine
not to exceed five thousand dollars ($5,000), or by both. A second
conviction for the conduct described in this paragraph shall be
punishable by imprisonment in the county jail not to exceed one year
or by a fine not to exceed ten thousand dollars ($10,000), or by
both. A third or subsequent conviction for the conduct described in
this paragraph shall be punishable by imprisonment in the county jail
not to exceed one year or in the state prison, or by a fine not to
exceed twenty-five thousand dollars ($25,000), or by both.
(e) As used in this section, "person" means any individual,
partnership, partnership's member or employee, corporation, limited
liability company, association or corporation or association
employee, officer or director; "owner" means the person who owns the
original master recording embodied in the master phonograph record,
master disc, master tape, master film or other article used for
reproducing recorded sounds on phonograph records, discs, tapes,
films or other articles on which sound is or can be recorded, and
from which the transferred recorded sounds are directly or indirectly
derived; and "master recording" means the original fixation of
sounds upon a recording from which copies can be made.
(f) This section shall neither enlarge nor diminish the right of
parties in private litigation.
(g) This section does not apply to any person engaged in radio or
television broadcasting who transfers, or causes to be transferred,
any such sounds (other than from the sound track of a motion picture)
intended for, or in connection with broadcast transmission or
related uses, or for archival purposes.
(h) This section does not apply to any not-for-profit educational
institution or any federal or state governmental entity, if the
institution or entity has as a primary purpose the advancement of the
public's knowledge and the dissemination of information regarding
America's musical cultural heritage, provided that this purpose is
clearly set forth in the institution's or entity's charter, bylaws,
certificate of incorporation, or similar document, and the
institution or entity has, prior to the transfer, made a good faith
effort to identify and locate the owner or owners of the sound
recordings to be transferred and, provided that the owner or owners
could not be and have not been located. Nothing in this section
shall be construed to relieve an institution or entity of its
contractual or other obligation to compensate the owners of sound
recordings to be transferred. In order to continue the exemption
permitted by this subdivision, the institution or entity shall make
continuing efforts to locate such owners and shall make an annual
public notice of the fact of the transfers in newspapers of general
circulation serving the jurisdictions where the owners were
incorporated or doing business at the time of initial affixations.
The institution or entity shall keep on file a record of the efforts
made to locate such owners for inspection by appropriate governmental
agencies.
(i) This section applies only to such articles that were initially
mastered prior to February 15, 1972.