I think the crux of the issue is that "force" isn't binary. People think you can "force" someone off your premises without injuring them to such an extent.
Is your position that it would not have been possible to remove him (even without his cooperation) without injuring him to this extent?
I don't know. It's easy to criticize after the fact on an online forum, especially by many who have never been in physical confrontations and seem to have an expectation that they'll never be harmed no matter how they behave.
The security staff is charged with removing someone from an aircraft, without knowing their intentions, who's already acting strange by refusing to leave in the first place, and acting in limited space with lots of other people around. They could've done a better job, but it also could've been much worse.
It's easy to criticize, because it was a bullshit response by both the airline staff and the security staff.
They needed the seats to move their staff operationally. To do that, they needed some passengers to volunteer to not fly. To do so, they needed to offer incentives, not demands.
The airline's problem is that they didn't want to pay enough. So they used force, not only that, they used public security (police) to enforce a private contractual matter (not providing travel, even though the passenger was in complete contractual compliance).
The security staff were briefed, and if not, should have waited until they were. He wasn't "acting strange", he was upset at not travelling as he had paid for, and wasn't been offered a reasonable alternative.
Excusing this behavior is allowing it to continue.
The airline should be able to ask any passenger to vacate its property at any time for any reason, just like any other business. Passengers should not have to volunteer. Refusing to comply with this request is trespassing and justifies removal by force. This may well be a breach of contract, and that should be resolved post factum, in civil court, like every other business dispute.
You don't have to guess or use your imagination. You can find videos of even more unruly people getting forcibly removed from premises without such severe injuries. Here's one of a passenger getting forcibly removed (and I'm not even claiming it was all that great): https://www.youtube.com/watch?v=e2CR_zuzNwg
I would also suggest considering that e.g. bus drivers face noncompliant passengers (non-paying, even!) far more frequently, and they have pretty good peaceful means of dealing with them.
Sure, like I said sometimes it goes better, and sometimes it's worse.
Clearly it was adjudicated that it was excessive in this United instance by people qualified and knowledgeable of all the factors but that doesn't override that fundamental point that when force is used then injuries are possible and probable.
> but that doesn't override that fundamental point that when force is used then injuries are possible and probable.
Sure it does. Because force isn't binary, which circles us back directly to where I made this point above. Your logic only makes sense if you treat "force" as binary.
I already answered your question about the degree of force in that I don't know, and that "people qualified and knowledgeable of all the factors" have already decided for this particular instance that it was excessive.
> It's easy to criticize after the fact on an online forum, especially by many who have never been in physical confrontations and seem to have an expectation that they'll never be harmed no matter how they behave.
Now you're just using ad hominem to make your point.
Is your position that it would not have been possible to remove him (even without his cooperation) without injuring him to this extent?