Absolutely no one should be cancelled. Should there be consequences for actions? Yes. Harsh consequences, in some cases. But cancelling someone for having a opinion that differs from mine? Cancelling someone for celebrating something that I - or the whole human race for that matter - defines as "bad" or "wrong"? Nope.
The people doing acts like these should get treated with the same amount of force and should be punished accordingly, whatever that might entail.
The people celebrating these acts and cheering on murder and terror. Let them show themselves as the stupid piles of flesh they are, so that we know who to avoid and have examples of what not to turn into. But let them say whatever it is they want to say. I don't condone violence of any sort, but I will fight for everyones right to voice their opinion, no matter how hard I disagree with it or no matter how wrong (legally, morally...) it might be from my point of view