Because the security personnel is typically trained to step in only when needed. I assure you that person was within several feet of the bus driver with an eye on the situation (and perhaps a finger on whatever might have been in his pocket...pepper spray, most likely).
Everything you've said I agree with, except for the pepper spray thing. Only reason I bring it up is that people read about pepper spray on an internet forum, run out and buy one, and then have no idea how to use them.
Pepper spray in an enclosed crowded space with children would have to be a last ditch effort when there is no other choice. Even then it can make a situation worse, so it's likely to remain in the pocket. Consider them "area weapons" as you'll potentially affect anyone in the sprayed area. If the bus' ventilation system is active...
As SSR said, I'm sure that the UC was vigilant and ready to react, but it would have been to get the guy off the bus, or put him on the floor if necessary. Imagine how difficult that is in an already narrow and cramped space like a bus stairwell / aisle. If there were more people in there being "the man", it would complicate things. Usually when "the men" and "the women" are not jumping into a situation, they are actually evaluating many different factors in their head, like protecting "their family" from the situation unraveling in front of them.
The only "failure", if you can call it that, is the lack of security
responders in the immediate area of that loading zone, as the "bus operations" person said. If there is a crowd, there should be a couple of uniforms in the immediate area. Maybe they were busy on other calls, but there should be a surplus of uniforms to respond to multiple incidents, and cover the unmanned posts. Uniforms go a long way toward diffusing situations, and unless WDW relies on UC's breaking cover during a shortage, this was a potentially bad situation. The UC's don't seem to like breaking cover.
IMO, the UC should have ID'd himself and diffused this right away. There is no sensitive nature about "their cover"; this is an amusement park not a narcotics squad infiltrating underworld gangs. Most of the people who saw this online and in the park will forget the UC's face right away. Anyone who has a worse motive for remembering the UC's face, well WDW has worse things to worry about at that point as they're planning something that no amount of cover will help.
I'm also not crazy about the supervisor taking the driver off the bus without instructing the passenger off the bus as well. I hope the driver secured the bus and removed the key by this point. Stressful situations always change the ways that things are handled, and not everyone responds perfectly.
I have family driving buses and this reminds me of statements they have made about the risks involved, the risks that the management puts them in, and the lack of procedure and preparation that they are given for these situations. Frankly, if I were the driver, and I was choked, I would have immobilized the guy and worried about it later, because I'm not getting choked a second time. I think this driver did that because the idiot calmed down a bit when he realized he almost got his trachea crushed for trying to choke the driver.
As for the "buses being bad" my experience is that the passengers are usually the problem, and this is why I avoid them. After commuting for many years, I have had to resist the urge to drop many a fellow commuter for being a wise-guy, etc... because between the driver's frustrations and my blood pressure going up, it's just not a good situation. Most of the time it's fine to let the moron fizz out and act like a putz for a few minutes... it's like feeding trolls, you tell them to shut up and it fires them up some more. The other 47 people on the bus know he's a moron, you don't need to tell him to shut up.
), I'll make clear that I was in that portion of his camp in which he's trying to get many of you to chill out without knowing all of the facts and after having only seen the second half of an incident on video. That doesn't strike me as a terribly controversial position to take.
!!!!!
