If you do the above I hope you get prosecuted for trespass by the BTP.
Risk you take. It's my opinion that by refusing any option of accepting a caution, the matter would be dropped before court. And if it wasn't - any moderately eloquent defendant could make the case that their actions were no more unreasonable than those of a railway company that expects to keep passengers effective hostages for several hours during what should have been a short trip.
Juries. Wonderful things...
If you fall over and break your ankle whilst walking along the ballast in unsuitable footwear are you going to sue Network Rail as well?
That would be silly. What I'd expect is a less safety-obsessed and more practical approach. If we assume they dont intend traincrew to take the risk of physically restraining passengers for their own safety, those crew should be able to hypothesise about where a person might successfully get off the railway on foot, and how practical it would be to reach said location. Persoinally I'm the kind of person who always has suitable footwear, but again its an info thing
The current policy wouldnt let people make informed decisions as to how far they had to walk and over what terrain, so people might make poor choices
My whole point though was that by keeping everyone on the train and not providing options, the railway company makes it far more likely that people will take control of their own destiny in ways that are unhelpful. Such positions actually increase the risk to life, even when, as here, intended to reduce it.
The secondary point was theres no way it was acceptable to be stuck out there that long.