Mosque at Ground Zero

[Glidergun]

I wonder what the logic would look like completely turned around. I
wonder if you'd say that building a monument to the Crusaders in Medina
or Mecca was a good idea?

This, however, is not "the logic turned around". You are equating a mosque to a Muslim version of a monument to the Crusaders. Rather, you should consider a Christian church in Medina. I'm pretty sure they exist. Or, to make the equivalence even more effective, perhaps we should compare it to a recent terrorist attack by a Christian. Like a church directly across the street from the site of the Oklahoma City bombing.