It’s bullshit. The reason most ‘Karens’ are female is because when a man tries this sort of behaviour, authorities are much less likely to piss about. In the USA, the cops take a much more robust approach to troublemakers than the cops over here do.
I ‘held up’ a building society for a similar reason in 2002 but all I did was sit in a chair and say I wasn’t leaving until I got my passbook. (I’d run out of cash money and needed to withdraw in order to eat. Also, they’d promised me the passbook the previous week.) I also ‘held up’ a hotel in 1998 with a couple of live toads (but all I wanted was to know where their pond was so I could put the toads in the pond). Screaming, threatening and throwing jackets on the floor would have got me arrested, just like this stupid incel here.