You may wish to consider their PR organ leaping to a conclusion and accusing the US of a War Crime. That is political speech
Maybe I misread their statements, but I was under the impression that they didn't conclude it was a war crime, but asked for a thorough investigation to determine whether it was, considering that disproportionate attacks on medical facilities are indeed among clearly defined war crimes. Obviously this was also a statement crafted by
PR professionals (and/or fundraisers) to get attention in the media, but I don't think it was entirely unreasonable or political. Everyone accepts that civilian casualties are unavoidable, but medical facilities enjoy a special protected status for a reason. You don't shoot the medic. Reminding people of the Geneva Conventions isn't political, and they wouldn't be doing their job if they didn't. I don't think they're political (or anti-American in any way), they're just doing their job.