Because no matter how harmful he may have been in life, his death is probably more harmful.

We had enough problems without tit-for-tat assassinations of anyone that anyone else dislikes.

The Luigi assassination didn’t come out so bad since there wasn’t a strong political back and forth (there was some, but he wasn’t really a political/public figure, just an arsehole ceo, and didn’t make a great wedge issue), this one is much more dangerous, and yeah, probably it would have been better if he’d continued his harmful speeches from a limited platform than become and excuse for so many “justified” attacks on the left.