The upside for the pope is that it doesn't become a thing. If he receives Trump, it's a one day story. If he refuses to meet him, it's headline news for days if not weeks -- and it plays right into the hands of Trump's most rabid supporters and Francis' critics in the Church.

Francis should meet Trump, shake hands, give him a Vatican key chain, and then get him the hell out of there. 

Actually, the key chain is optional.