Not sure why your first post would have been down-thumbed TCat except maybe somebody thought that you had not studied the 1988 SSPX concecrations that resulted in ex-communication. I'm not sure that your question clearly betrays ignorance of those points, and, in any event, think down-thumbing you for that would be a lack of generosity.
But if it happened, I think 2 things would happen: 1. Any bishop involved bestowing or receiving would be excommunicated. 2. The traditional world including the mainstream SSPX (sorry for the oxymoron) would marvel and celebrate +F's restored parts of manhood though some would do so quietly pretending they never thought he'd lost them, it, or whatever.
Would the excommunications be valid? I think not, for 1 of at least 2 reasons. 1. Necessity. 2. Who's going to VALIDLY excommunicate them?