I can understand your frustration, certainly, after having H Sea Star ninjaed by a warlock (who doesn't even kind of benefit from Spirit). However, I must urge you to NOT ninja because you then just become as bad as them. It's a vicious cycle. Someone does it to someone else, they get bitter, do it to someone else, who gets bitter, who does it to someone else...
Remember for every asshat you will find a respectable and respectful player. It just may take longer to find them because they don't call attention to themselves.