Ok, let’s send them to the Hague I guess? Why do you think this is an important point? Hamas isn’t actually a legitimate organization that signed on to international law and would ever care what “legitimate warfare” is. They just went into Israel and murdered a bunch of civilians. If these fighters are caught whether the UN thinks they were wrong is the least of their problems.
And none of that makes Israel attacking a hospital (or just the blatant collective punishment) justified.