Now if they were police officers...
...as I believe Det.Sgt. Cooper still is, then they might have grounds for appeal.
However, they are mercenary footballers - just like everyone else.
It is unfortunate that the borders of the Isthmian League have shifted on a scale normally associated solely with Poland, but everyone's had nigh-on 18 months to prepare for what wasn't a wholly unexpected situation.
They could always go back to being a works team in the Combined Counties League and maybe throw their sports subscription money at something else.