Chapotraphouse

The Romanov kids were executed because of logistical extenuating circumstances and some degree of panic about the Whites imminently being able to retrieve them. If that wasn't the case, the kids could have just been held in captivity for the time being. It was to the best of my knowledge the actual intention of the central leadership of the Bolsheviks to try Nicholas II and spare the family, though they endorsed the killing once it happened because it was a reasonable response to the circumstances.

That said, even if that specific "scare" of their retrieval didn't happen, it would be a continuous liability down the line, and I think the singular centrality and religious importance of the royal family makes them maybe not a great comparison to "every single child born to any noble household in the state of France".