i don't condone child murder, but if you don't want uncontrollable violent mobs of people to seek bloody retribution and vengeance upon you and your family, perhaps don't personally lead murderous pogroms against minority ethnicities and political dissidents for decades, and maybe don't keep your entire nation in poverty and famine for generations while you and your family live in the finest luxury available to man.
There are certain moments in history where there's just too much at stake. The end of the various monarchies of europe was one of them. If you don't want a monarchy to come back you almost always need to put an end to it thoroughly.
Hereditary systems of power are stupid and cause this scenario.
It's bad that the kids were killed, it's their parents that killed them.
If you claim that God says your kids get to rule over everybody else there's one really obvious thing that's going to happen to them if people decide they don't want to be ruled by monar hs anymore.
Also their parents were so concerned with their safety instead of just fleeing they loaded the kids clothes down with giant jewels to the point it caused the kids to take longer to die because they had a rudimentary ballistic vest on.
Yeah, I consider it like the Israeli children who died in the crossfire that came from Hamas, i.e. that it's the fault of their guardians involving them in a monstrous political project where such things are not only possible but somewhat likely.