TAAT - moving children from seats on public transport

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I should have started this thread the other night just after it happened but was so tired, and just haven't got round to it since.
This is not really an AIBU or even an WWYD but more of an wIHTTPTSFO (wish I had told this person to seriously fuck off).
Kings Cross train at the end of last week ...walking down platform to the train, kindly guard asks if we're about to board train ....tells us it's not going to be used ....tells us which platform train is now leaving from.
The twin 4 yo and I are therefore the first people to board new train. Everyone who gets on it is mightily pissed off for having to get off train, walk a long way to new train, etc. it's the end of the week, etc, etc.
Newly appointed train has different seat configuration to the original one, on which we had booked seats.
I sit in the table seat with the numbers nearest the ones we had. Little gremlin man smelling of booze gets on and says "excuse me, is this your child? She's sitting in my seat?" I say "well, erm, the seat configuration is different on this train, we also have booked seats" Him: "I don't care. I have seat x (aggressively) are you going to move her?"
I didn't know at this point that when trains are changed all bets are off as far as seat bookings go, I didn't want a scene, was knackered and just thought the easiest option was to move.

But wasn't he an absolute charmer? I know for a fact that if I'd been a 6'4" bloke he wouldn't have said a word. I'm not losing sleep over it but it really annoyed me at the time that someone so go about their lives being so thoroughly unpleasant. He knew I was in no position to wait for the guard to arrive if we'd called him ....
I just had to share this with you after reading the thread about airplane seats. WRT that thread I just cannot get over people trying to manipulate other people, using their children to do so.

Explained in OP:

This is not really an AIBU or even an WWYD but more of an wIHTTPTSFO (wish I had told this person to seriously fuck off).

I still feel guilty about a reverse situation.

I had booked seats for my two then very small children (3 + 1, that kind of age, maybe 4 + 2 at the oldest) from a local station to Edinburgh, a journey of some 5-6 hours on a normal day, which I then did several times a year. It wasn't a normal day, as it turned out - for some reason that I can't remember, there was an absolutely almighty travel mess going on, and the train was heaving. I think that flights had all been cancelled and people were taking the train instead. The aisle was full of people standing, all the way down the train through every carriage.

All of us had paid and booked seats, because for such a long journey I could not manage 1 child on my lap while entertaining the other.

I managed to find our seats, which were occupied by 3 late middle aged ladies - not elderly, not frail, but not young. I (I hope politely, I was a little stressed) pointed out that these were our seats, booked and with reservations marked, please could we sit in them?

They did get up, and then stood glaring at us for pretty much the entire duration of the journey.

I still feel bad about asking them to move, over a decade later - they were older, I was younger. But the children were quite simply too small to imagine standing up in the aisle throughout such a very long journey, with people moving up and down through the crush at every station, and were already very frightened by the crowds. Should I have packed us all into 1 seat? Taken turns to stand? I just don't know, even at this distance. Was I rude? Entitled? Or just trying to do my best with 2 small children on a very long journey?