perhaps, but it was an ongoing civil war where leaving one of them alive could have led to them being captured by the Whites which would have been a huge boon and rallying point for the disunited White movement. with Puyi it was different because the right KMT were republicans too and would have probably executed Puyi, especially since he had been a collaborator of the highest order with the Japanese. if he'd been captured by the enemy then it wouldn't have been potentially disastrous for the CPC in the way that capture of a Romanov by the Whites would have been for the Bolsheviks