I have explained why, multiple times. You just don't want to accept it (fine, this will be determined at Nuremberg 2,0, not by you or me, here)

The sub knew it was clear of any Iranian guns, for over 100 miles in every direction, once it had sunk the only (unarmed) Iranian asset within 100 miles of it. Thats not the same as being within (or close to) Iranian territory.

Hence, the lack of threat, as per the established laws of naval warfare, neccesitate some attempt at helping survivors. The sub was in the immediate vicinity of the ship. Not 800 miles away firing a cruise missile.

To still maintain that, even in that situation, there's still some theoretical threat means that you're effectively trying to say that in NO conceivable situation do the established laws of naval warfare apply, in practical terms. For anyone, anywhere, ever.

In any case, this is all an academic exercise. In this world order, no laws - international, military, or common decency - apply to the US or its chosen allies.

Justice will have to be served the old fashioned way.

This is a rare case of an HN discussion on international law where there is something approximating an RFC that we can just go consult on these issues --- it's the San Remo Manual, which is trivially Googlable, and consists of a series of numbered paragraphs. Cite the paragraphs that support the argument you're making about the unacceptability of sinking a flagged enemy warship simply because the attacker knows it to be unarmed.

The guys on the Iranian warship also knew they were on a warship. I mean come on. What’s the expectation here. This isn’t tag on a kindergarten playground. People are gonna die.