If they are banning all political adds, across the board, I would say no. That's their right. I think having a break from political adds would be a welcome thing. If they choose not to see any politics on their platform that's their decision. However, if they only ban certain adds or certain individuals then there is a problem. Free speech is free for everyone. Advertisers pay for their spot on these platforms. If Twitter doesn't want to accept advertising money from any political campaigns that's their right to refuse the business. If they are talking about banning political speech, or politicians accounts, then that's an infringement on the first amendment. But if they're only talking about banning ad's then I would say no.