They're maybe trying to use the same law that Locast[1] is: there's a specific carve-out in the law about rebroadcasting for nonprofits: "an exception in U.S. copyright law (17 U.S.C. § 111) for retransmission of television programming by non-profits without charge or any purpose of direct or indirect commercial advantage (besides the costs needed to cover the operations and maintenance of the retransmitter), which was originally intended to cover over-the-air translator stations" [2]

[1] https://www.locast.org

[2] https://en.wikipedia.org/wiki/Locast#Legal_challenge