I say let 'em have some fun. Titans have had a super that gets them precisely 0 crucible kills for the last year. We probably all owe them a few deaths. That said, even in mayhem you can still take them out if you're quick - got one down yesterday who missed me with 3 hammers* with a regular pulse rifle. *luck aside, I'm guessing he/she didn't have flameseeker on. Either that or they're the worst shot ever.