Sometimes a guy just wants to feel like a tough macho man who can handle things and save the day, okay. It is perfectly normal. Popp is not immune to this and he likes when he can do it by shooing away a normal spider instead of fighting off demons and monsters, which is scary.

"Everything I'm scared of makes sense from my point of view! Lions. Skeletons. Getting a shot from the doctor..."

Popp does not want to openly cop to being silly, he wants to be seen as reliable, and is on the cusp of internalizing that those two things can both be true about someone. He's being very reliable right now, he hasn't dropped her or even crashed into anything!