The pros and cons of 'commuting' is a complete and utter red herring here! These are the issues that will land people neck deep in the brown stuff:
1) Dressing in uniform, and using an airside ID, to access the secure area whilst NOT ON DUTY, is both a security breach and I'm fairly sure, in the UK is breaking the law!
2) Receiving a Benefit in kind, (free travel) without declaring it for tax purposes, is tax evasion.
3) Anyone listed as supernumary crew, is engaged ON DUTY which must count towards FTL limits. Failing to declare such duty time is definitely breaking the law, and is wreckless.
Which category are these FR pilots in?
This can't possibly end well!
These folks are extremely exposed!