This.
With the greatest of due respect to
@bb21, the view expressed in the longer post is essentially summed up as "I want to avoid conflict so I have an easy life", paraphrased.
Telling me to move coach would have resulted in a formal complaint against the guard for failure to enforce the commission of a criminal offence under Byelaw 7 unless it was an invitation to move to first class for free (which Northern obviously don't have, but where it does exist it's a wonderful passive aggressive solution to this sort of problem, people refusing to move out of reserved seats etc).
Frankly, if proactively dealing with ASB isn't part of the guard's role any more, and miscreants no longer need fear the guard, then it's time we follow Merseyrail throughout the network and recruit some staff whose job it is to challenge ASB, even very minor ASB, and prosecute on a zero tolerance, no warnings basis. Minor ASB leads to major ASB, and if passengers can't rely on traincrew to keep them safe and comfortable against miscreants then the railway has no real future for more vulnerable people such as lone females, and that is, bluntly, completely unacceptable
The upshot of that is simply that in the face of rapidly increasing petty crime and ASB that the railway ceases to be a safe environment. And that is not acceptable.
So guards either need to accept the risk involved in challenging ASB, or we need bouncers on trains like Merseyrail effectively have. It isn't OK for us to collectively sit back and let this happen, and it DEFINITELY isn't OK for staff to suggest, per the above post, that if they're not willing to deal with a situation where a criminal offence is being committed, however minor, that passengers may not do so either.
In short I will continue to verbally challenge ASB on trains I travel on, and if I receive resistance from staff about this they will be in receipt of a formal complaint (or if there's any suggestion I rather than the miscreant should leave the train, I will be texting 61016 myself), thought that is yet to actually happen.