But there is no logic or legal ground for trademarking the word "monster" or the green/white colours in a logo. It is all about bullying smaller companies using their much higher budget.
Suing indie game developers is not a way to do it. There's a good chance these lawyers need to be paid much more for the time of dealing with this case than the devs ever had available.
What’s not okay is how it’s being “defended” here. This is just abuse.