I feel like it needs to be possible to remove and/or replace team members simply because of the nature of private servers.
People don't tend to stick around for long, and with the limited selection pool it can be hard to piece together a team that you can actually trust and rely on.
In saying this..... it should be incredibly hard for this to occur, such as a LONG inactivity time for the player being removed and the removal of items in their personal bank.
This is simply because items gained by one ironman (or group in this case) shouldn't be able to benefit another ironman/group (seeing the group as a single entity here because that's what you signed up for - personal effort ignored).
TL;DR - The player should be able to swap teams (in extreme circumstance), but at the cost of all their personal items.
(edit: if my team is reading this - dw i trust you boys )