It's not just episode 2. It's a theme throughout much of the series. And it actually serves some sort of purpose.

Y'know, his initial character seems to be similar to a hero's best friend who's a goddamn wimp who gets corrupted by the bad guys, or something or someone else, by pushing on his Non Action Guy status and giving him just enough power to go above that, and turns into a raving mad A God Am I villain and the hero must either kill him or bring him back to their side by beating him in combat.

Except, this time, he's actually the main character. To be honest, Hayase was quite an arrogant, delusional, raving mad prick when his future teammates first met him with a quite reasonable offer to take Linebarrel off his hands. Remember he was pretty much a civilian at that point, despite having been revived and given power beyond normal people, and a complete novice in combat, yet acts like he's numero uno. Shit, I was pissed off by him at that point.

It's not hard to see why his teammates treat him like a contagious dirtbag at the beginning given how low a first...and second, impression he gave them.