> maybe there is no one who posts in a similar style (TBH I'd expect most to be parody accounts) who has achieved sufficient popularity to compete

A couple pages down there are non-@realdonaldtrump tweets scattered here and there, always in pairs as far as I can see (https://twitter.com/majorbear70/status/1286690669826842626 & https://twitter.com/DavidWaddell5/status/1127214256636813313 https://same.energy/?q=I+heard+Bill+Clinton+might+be+joining..., and https://twitter.com/RealWayneRoot/status/1161435864506884096 & https://twitter.com/Mcphie00/status/1163080988085358592, Control-F to search), except scattered individual tweets from @RealDonaldTrFan