Because a Walkerbot came on the thread attacking Trump so Walker is fair game. Walker is a GOPe default candidate who has no chance to win a general election.
I think he was just commenting on the subject of the thread, a subject that has to make anyone who has hopes for Trump feel more than a little sick and queasy. It’s Trump who displayed idiocy here, and I think it’s fair game to comment on that, given the subject of the thread. Don’t you?