I'm kind of on the fence about it.
On one hand, it feels like a complete waste of time. The fight would be fairly one-sided unless Conor somehow pulled off the unthinkable, and I'd probably rather just see Conor spend his time focusing on his UFC career than getting tooled by someone in a completely different sport.
On the other hand, Floyd isn't likely to lose a possible 50th bout regardless of who he fights, so why not make the event as much of a spectacle as possible? It's near impossible to make an argument than there's anyone other than Conor McGregor that would make a bigger opponent for Floyd. The whole magnitude of the event, seeing boxing and MMA fans blending together, the build-up (especially if Conor did some crazy, Ali-level shit like going to Floyd's gym and starting shit), and the electricity of just seeing them in the ring together no matter how forgone the conclusion might be... It would almost be worth it. And in the chance that Conor succeeded, then...