The First Amendment lets him speak about everything else, and his range of material is bizarrely huge and off-topic for any other politician out there. He collects what he considers injustices and must rant against them - this is where the threat of being fined keeps him in check. We hope. So far it has done nothing to remove him from the race (though the debate about the seditious acts and whether a court prosecution is required to remove him from running is ongoing).