Without Luke on the wan show Linus would be useless. It would be one guy saying whatever comes off the top of his head ranting uncontrollably about everything.
He knows when he goes off on a subject and Luke is there that Luke is going to challenge him if he’s being an ass, so you get a better quality of content from Linus than he would produce on his own.
Linus isn’t going to watch his mouth, that’s honestly his shtick.