Absolutely unacceptable to have violent incidents towards staff or other passengers, full stop.
Am I suprised it happened at Victoria, no. Nor would an incident at platform 14 at Piccadilly suprise me either.
The delays at Victoria are shocking, and some of the decisions made there seem to be designed to annoy passengers. The one that used to always get me was the 6.30pm Northern stopper to Liverpool, it would pull out if the siding onto platform 3 at around 6.15pm sit there with the doors locked until around 6.28/29pm with passengers getting more and more agitated. I'd always assumed it was because it needed a guard or something but if someone told me it was the staff having bets on whether they could start a fight or cause someone's blood pressure to cause a heart attack, I'd probably accept it as a possibility.
Some of the decisions made on the railways at the moment seem to be a social experiment on how angry people can be made before violence breaks out. A lot of it comes from the disjointed nature of the current system....
What's that your travelling towards Barrow to get the last train out, your train is going to miss it's connection by 5 minutes, do they hold that train, nope. FU, you can wait 30 minutes for a taxi and the take the best part of an hour to travel the 30 minutes it takes by train. This didn't happen under BR.
Your train is cancelled, you need to make a connection, can I have authorisation to travel on another service, no FU.
Train cancelled, need to get a replacement bus, where's the bus going to go from? Any signs? Any staff taking passengers to the location? Any staff directing passengers? No, FU.
I know the above sounds extreme, but the current system has no accountability, if you can find someone they generally point the finger elsewhere, it's always another TOC, or software that doesn't do what it has been doing for the last 20 years.
I travel a lot and so have a good handle on what to do if there's issues. Most people don't, and get basically no useful assistance or information. We have a system were people are happy to hand out penalty fares when listening would be more helpful. One of my members of staff tried to buy a ticket for the next train but the TVM wouldn't sell it so he gets on, no conductor, tried to buy at MCV and yadada penalty fare. Now I know that what happened there is the train was coming soon and it was too late for an advance fair, greyed out that train and the software is too useless to just offer a peak single or something. I've explained to him how to avoid this in the future buy picking the 2nd train and trying to get a day or return. But you can see why the public get frustrated.
Labour had one decent policy and that was nationalising the railways, very popular with the public. I think people understand what's wrong and don't think anything other than radical surgery will fix it.