You and I have the privilege of saying what we want, because we don't have to work to have influence with other nations. Those that do have to take a more measured path.
The UK is quite embedded with Israel in a number of ways. This is the ugly reality of foreign affairs. If elected, Starmer will have to build relationships with the future Israeli govt. Screaming genocide won't work.
You can condense all of this into one of the most stupid comments I read about last night's events, that "Labour had voted to continue bombing". As if the vote had any bearing whatsoever on Israeli actions.
What is happening in Gaza will not stop until several conditions are met. One of those being the release of hostages, and the other being able to demonstrate some sort of victory over Hamas.
I use the word demonstrate because, of course, you cannot defeat an ideology with weapons. But, none of this is about cast-iron, delineated truths or clear moral boundaries. If it was it would be easier to take a firmer political position.
I agree with you that it is likely that Israel will use this attack as an opportunity for a 'final solution' to the Palestinian thorn in the side. But it isn't tangible enough yet for other states to proclaim it as such.