This isn’t even the right color scheme for the character, so it’s not like they misinterpreted the sprite
Rock over here looks like he shit himself upon seeing a Mettaur and is trying (and failing) to pretend he didn’t.
Mega Man doesn’t even use a gun, he uses a Buster. The only time Mega Man has used a gun are instances that parody this boxart or rare occasions like when his internet incarnation uses the Gun Del Sol during crossover events with Boktai
I don’t know which I love better