Shatner has said repeatedly that he barely KNOWS Takei.
Yeah they worked together 50 years ago, and on the movies, but face it, Sulu was a minor character.
Shatner was only close to Nimoy, the other actual STAR on Star Trek.
He's mentioned being friendly with DeForest Kelley, but pretty much as a "work" friend.
The others he barely interacted with outside of the show.
He even forgot Chekov's real name, when introducing the cast at some ST event.
To this day, he still pronounces Takei as "Ta-kye", which George just can't get over.