Indeed.
The rule could (and perhaps should) be changed to instead say "professional use", which would leave out the hobbyist vloggers who are basically just funding their hosting and a pint or two on a Saturday evening (and almost certainly not declaring it for taxation as they probably should be) - but as things stand I wouldn't say it's grey - if at the time you are photographing/filming you expect that you will receive money in return for doing so, even if only a little money, then that's commercial use.
Having said that, staff should be polite and non-aggressive at all times, the only time aggression might be justified is if you need to remove someone from immediate danger of death or life-changing injury (e.g. pulling someone back from a platform edge as a train they haven't seen is approaching at speed). If staff get angry with people for any reason, they're in the wrong job, even if the passenger responds angrily and thus needs to be removed from the station professionalism is always key. And staff do need to be professional enough to see if a disability might be involved and might affect how someone reacts, too (noting that the vlogger in this case is autistic and very obviously so).
It is true that the WCML platforms at Wembley are specifically controlled for safety reasons, but "I'm sorry, I'll have to ask you to leave the platform now for your own safety" is the sort of approach that needs to be taken.
Having said that, I did just watch it and the guy didn't seem to be *that* aggressive, more assertive. Politely assertive is fine when safety is the issue. I *think* there is also signage on the platform entrances there, so it wouldn't have necessarily been unexpected? (What I personally dislike is being told off for something that isn't intuitively not allowed and where there's no signage or similar - it's unnecessary embarrassment, which many autistic people, who often obsessively follow rules so long as they are aware of them, can react very adversely to indeed, resulting in a major altercation that isn't necessary).