Yeah, fulham can't just postpone it cos Steve Sidwell is tired. They'll put forward a case for the tube strike being an issue and 'safety' will be the key. Police will back them up and the fa have the final say. No way they will go against the home teams and the law.
It's not really a matter of them going against the law though. It's what happens next.
If Fulham can be shown to have not made a reasonable effort to get the game to go ahead (and providing alternate transport would surely constitute "reasonable effort", as well as providing travel subsidies, or importing more local stewards, or coordinating with Liverpool to use Liverpool stewards - if possible), then they stand to forfeit the game, and Liverpool get 3 points and probably 3 goals in lieu of the game - rather than the game being replayed at another date.
There is nothing about this that says "we had no other option" when looked at reasonably.
So the issue is not "will the game go ahead?" (and I do appreciate that a LOT of people have organised their weekly schedule and finances around the game going ahead - and they should be compensated for that) from the league's perspective - it's whether or not Fulham contravened Rule L.2, and what the consequence of that is.