I have this conciet that the vulcan preimieres hand their katra down to their successors generation after generation, so Messick has some of Saoron's memories, which include some of the memories from previous premieres that Saoron thought were interesting enough to keep. And this tradition goes all the way back to T'Pau. So Messick remembers Spock's Pon Farr...

Kenny and T'Lon both have some of T'Lok Smith's memories - those which each of them thought important to keep. Which is why Kenny knew that T'Lok's father has never worn a shirt since he retired from the Hanamalulu School of Music.

Thanks!! rbs