Jon the Most Honorable and True isnt even in the Night's Watch, that was just a lie to avoid being executed which Grey Worm strangely accepted. He's a member of the Free Folk now.
ps- I love the notion that Gray Worm, a guy who was neutered as a kid and went thru unspeakable evils to become a ruthless killing machine, was made to see the justice in a "lifetime sentence."
"Oh so you mean Jon will have to ride about on a horse looking forlorn? Yes, yes, no need to execute him for killing the Queen, this will suffice."