It would be a spectacular failure of logic to evaluate someones record on war based on a flippant comment (which you misrepresented) as opposed to, oh I don’t know, maybe if they started any wars. Considering that he is the first president in at least a century to not engage in any new wars, I think that might be a better signal.
The comment was made in response to the Barcelona terrorist attacks and was very specifically joking about what we should do to domestic terrorist groups that mass murder. It was also not his original thought. He cited a myth regarding what he thought someone else famously did to terrorists and said maybe we should do that.
Getting upset about what he actually said and in what context seems like faux-outrage or someone with motivated reasoning to try and find something to get upset about.
