The only thing that annoys Howard more than his godawful homeworld is optimists, because they baffle him. Thus, his only reaction to Hoshi is to be annoyed and confused, and snark at her and try to rain on her parade. In any future interactions he'll do this until she either gives in, or he gets so frustrated and storms off and declares her an idiot. That said, he feels a bit more comfortable with her than other shipmembers since they're around the same age, and thus she registers as less of a threat.