Well part of it is because of the false memories that was planted into him, and that would freak anyone out. Even kwamis.

"It's not okay! This...This place made me think Fu abused me. How could I think my dear old friend could...could..."

Sorry Plagg, but now your friend is in tears. Too bad Tikki or Ladybug isn't here for this.

Nino had braced for the ground when he got caught by Chat. He makes a deep breath to calm himself. "Yeah, I think so, dude. Never thought Wayzz would do that again, and I think the shield is even bigger this time."

He looks over to Wayzz with a frown and messes with the top hot he's wearing with his steampunk clothes.

"Poor Wayzz. This place is too cruel for him."