Earlier quoted context omitted.
Are the people they're up against really all that morally superior? I'm not making a whataboutist point, it's just that if you're picking a side you have to look at more than just one of them. So absolutely soldiers should be held accountable for their treatment of captives, and e.g. Israeli soldiers have been jailed for assaulting prisoners, but I don't see many Palestinians being jailed by their own administrative…
I would agree with some of the point you raise: no clear moral superiority of some of the people they are against. Do recall that that Israel has followed a policy of assassination based on political disagreement. People have been assassinated for their speech and opinion.
On a specific issue such as a particular crime or incident I don't believe whataboutist rhetoric is justifiable. In fact it appalls me. But I'm not going to boycott Israel on the basis of a moral argument for their behaviour in a conflict without also hearing why we're not also boycotting the other side too. There are several sides in that conflict. If we want to understand and address it, that needs to be done with the blinkers off.