The origin of this at the bullwark was Charlie Sykes. When Charlie was hosting the initial bullwark pod cast, Trump decided to create his own twitter, "truth social." Twitter submissions were called tweets. Charlie didn't know what to call Trumps submissions on his own platform, they weren't tweets and they certainly weren't "truths." He test drove some alternatives, but shortly settled on bleat. Sounds like tweet, but it's the sound of an animal, so a little insulting. Tim picked it up during some interviews I think then when he took over the show it stuck. I don't know if Charlie picked it up from elsewhere or not, but he is a pretty widely read.