Marco is totally that annoying little cousin that Sam never had. And is grateful for never having experienced, I think. He doesn't know Marco well and he'd...rather not have to talk to him too much until after Schmuz has his own body. It's not that he doesn't appreciate that Marco knows more about Yeerks and all. He just doesn't like the implication that he 1) is dumb and 2) didn't actually think any of this out before hand. He can, at least, understand that they don't accept that it's Sam in control all the time.

Schmuz is right with Sam about never talking to Marco, though. I think a lot of that, though, stems from being laughed at. He still has some pride, damn it.