I could ask “Why do Christians waste time on this?” on about 2/3 of the threads on the forum. It’s important to some people, and I try to respect that and just go read another thread if I don’t care about the topic, unless it is so beyond the pale that it doesn’t really have a religious connection, which is not the case here.
I personally don’t think a serious scholar of theology should be making remarks online, even in jest, about assassinating Jesus, or Moses, or Muhammad, or Buddha, etc. It’s disrespectful and to me it’s an ethical breach for a scholar. It won’t keep me awake tonight, but the guy deserves some blowback.