Wayne enterprises apparently encompasses stuff like defense industries and medical insurance; if someone who'd been denied healthcare insurance and was either dying or slowly watching their body die or fall apart on them killed Bruce in a similar fashion, how would his friends react?
Superman, the flash and even green lantern are portrayed as fairly understanding people (although Superman and Batman are literally best friends), but Wonder woman is decidedly not; thing is, if they found the shooter, some guy who could barely walk, perhaps shaking from whatever ailment that progressed because his health insurance decided to delay as long as possible (with the likely intent of waiting the guy's health out), what would they do? It's hard for me to imagine even Wonder woman hurting some guy who can barely stand, even though she's definitely one of the DC heroes who kills her enemies (or at least some of them).
I'd ask what if it was a person from the global South who'd been a victim of Wayne enterprises' defense industries but honestly given DC is an American company, I can easily imagine Western heroes pounding the heck out of an Arab or African person who'd lost loved ones to Wayne enterprises.
Of course it depends on the writer but that's a boring answer
If the Luigi is a normal person nothing happens, the Justice League is too button-down for that. Maybe Jason (Damien in tow? Depending on who's writing he's still trigger happy) goes after them but stops at the last moment cause the rest of the bat family talks him down
If their tragic backstory made them a proper villain things get more interesting, but I still predict that they would do a The Falcon and The Winter Soldier style "you have a point but this isn't the way to go about it". The villain either refuses to repent and dies by accident/their own hand or goes to Blackgate forever. Whoever inherits Wayne Enterprises (last time it was Tim) makes some token changes and the arc ends on a note of "incrementalism good, radical action bad"