Looking back over the last few pages, we've moved from "player who always plays the same character" to "player who always plays the same character, and torpedoes any game that won't let them".
These are not the same.
maybe a tangent:
A good friend back at school rode his pushbike into the back of a van. Fractured his skull. He recovered, no problem, but it took a while.
During his recovery, he continued to play in our D&D game. (Once he was well enough)
He played an elven ranger called Jethro Tull. Multiple times. Over several character deaths, change of campaign ... I think he tried to play him in Call of Cthulu ...
We gave him lots of slack.
Where the boundary lines are between Fractured Skull, emotional issues, personal preferences, just being an arsehole ... that is down to you and your table.
I think my point is: Cut people some slack.
One that I've just been reminded of is pronunciation, even when they're told the correct way. Calvary (spoken, not just typoed) for cavalry, curiass for cuirass, and one guy who always used to say p'ladin (to rhyme with Aladdin) rather than paladin.