Hey Joe,
I have that at 2 of mine, months and maybe 1 over a year, plus one who closed his account yet the name remains. Agora won't remove it??
A few at 1 hub are taking a break since not much is going on to discuss and I know they will be back.
Having said that, Agora may be willing to purge the list with adequate input, such as the HL asking to be removed then you suggest a replacement.
If I were you, I'd PM the person(s) and ask what their involvement will be if any in the future and take it from there. Also, have a replacement lined up to take the spot(s) or you risk being the lone wolf.
Good luck!