For those unaware, like the perp here, you can't wear election related material in or around polling places. It's called "Electioneering".
https://www.ncsl.org/elections-and-campaigns/electioneering-prohibitions
Texas (where this happened):
100 ft. of an outside door through which a voter may enter a building in which a polling place is located
Campaign materials/signs/banners/literature
Projecting sounds Referring to candidates/issues
Loitering
Apparel/buttons/stickers/placards
Tex. Elec. Code § 61.003 and .004
Tex. Elec. Code § 61.010