If they don't know what to say they shouldn't even bother with saying anything to begin with. And you're giving her too little credit, she has no need to pressure anyone if she has a good speech. Besides it seems you both don't even agree on what basis or context you're making this poll, Haruhi has the widest context of it while you just narrow it down to one thing, turning a blind eye to everything else.

Whatever, I have no interest in getting between your lovers quarrels. Though I think you should know Haruhi enough by now to not be so bothered by things like her liking maid costumes on cute girls. Specially if the cute girl is you.

[Or not. It's a shot in the dark but he doesn't care. It's either that or that Haruhi was drooling or doing something that Winry could consider as cheating with a girl dressed as a maid. Nothing else gives sense to this whole conversation anyway.]