R4 It both is and isn't odd that he's asked J. In RL you definitely wouldn't ask your ex's son to be your best man. But J is also Jolene's stepson so....
Something interrupted me during a conversation about David and I haven't managed to listen again - so don't know the reason for his not being K's best man.
No friends does seen odd at first. But there are plenty of Mnetters saying they can't find new friends, especially if they've moved to a new place (or back to an old home) after say mid twenties. Kenton was out of the country for years, and not very settled when he returned. So it is (for once, the SWs never remember to give people non Am friends) conceivable that, despite being the life and soul, he really doesn't have any very close friends.
Nigel was his friend. He would have been his best man. 