I don't suppose you have something like. . . oh, I don't know. . . a citation to the alleged Federal law that states this?
What Happens If You Disobey a Flight Attendant? - Law and Daily Life
(Pub. L. 103–272, § 1(e), July 5, 1994, 108 Stat. 1244; Pub. L. 107–56, title VIII, § 811(i), Oct. 26, 2001, 115 Stat. 382.)
Or shooting them in the head. Yup. Whatever it takes. But having watched the videos it seems obvious to me there was no beating. I didn't see one single blow landed or even attempted. It appears the guy was clinging to the armrest to resist police efforts at dislodging him. They kept yanking harder, and his hand slipped off and he came flying out, smashing his face into the side of a seat.
Too bad, so sad.