The chainsaw might be kinda violent, but it could still be done cartoonishly, like as a multi-hit weapon, and watching fighters vibrate with it could be amusing.
Though, honestly if Doomguy came out, I’d be as excited for him, as you are about “another sworder.” In fact, honestly Banjo is the only DLC fighter I got excited for as honestly I’ve never played the games the others are from, but admittedly they still look cool, and fun. SSB got me into other series I used to not be into, so I see nothing wrong with experiencing new characters from series I never tried.
I admit, I’m more excited about the Cuphead & Rabbids Mii costumes. (The Cuphead one looks very convincing, like Sans.)