For maybe the first time since he got here, Shido's reaction doesn't surprise Akechi. He's aware of how it looks (he relies on it, in fact) so he's not going to let himself think that it's strange or hope for a different reaction.

That answer, though... Akechi's expression darkens behind his mask, and he's glad that it's the sort of that covers his entire face. He's pretty sure he's doing a bad job of keeping the annoyance, frustration, and confusion at that answer hidden. It's obviously Shido's doing, though Akechi can't begin to imagine how, so the fact that he won't admit to it gets under Akechi's skin. He's silent for a moment before he clicks his tongue.

"If you wear yourself out, I'm not slowing down for your sake." Telling him to stop is as bad as admitting that he dislikes it, so he'll focus on the practical aspect instead.