when in the last couple thousand of years, if Jews had wanted to stone apostates to death, would they have been able to do it? The diasporan condition doesn't really allow it.

You sure about this? I don't know much about this topic, but I remember reading somewhere that 200 or more years ago Jews were often allowed to give punishment to their own people within diaspora. They couldn't stone a Christian/Muslim from the majority population, but they could stone (or otherwise kill, or otherwise severely punish) one of their own -- unless the given sinner already converted to Christianity/Islam and left their community. So converting to majority religion could be safe, but converting to atheism or some heresy within Judaism would not.