I've read that in the DAN O2 manual too, but that doesn't mean that they are making any sense.
This is exactly the same issue that I have with DAN in a number of other areas - trying to apply "doc-speak" and "doc-think", where one assumes that every doc is the same as THEIR docs.
This kind of "tunnel vision" is exactly what they garf about with divers and DCI (and they're right), but then they practice it themselves (which is wrong.) I went around with them on this with O2 being available on my boat (as a PRIVATE vessel, not a charter) and talking with them about my "little speech" that first-time divers on my boat get - the O2 is in this cabinet, and I encourage you to use it if you have any reason to think you might want to after a dive, even if you feel fine, if you think you might have screwed up somehow - the bottle is dirt-cheap to refill.
Well that triggered some discussion here a few months back, revolving around the "you're administering something" (no I'm not - the person who grabs the bottle is doing it themselves) culminating in my calling DAN and getting the actual doctor on the phone who wrote their "policy documents." He was at the time clearly thinking in "doc-speak", and while their parrots on the phone did indeed start with that position, when I got done talking with the actual doctor who wrote the material he conceded that (1) it would do no harm for someone to pull the bottle and breathe it, and far more importantly, (2) doing so might prevent a hit that someone would have otherwise taken.
Then you look at the DAN "incident report" with the guy who breathed a cylinder with less than 1% O2 in it. They list as "contributory factors" that the diver was overweight. That is, to steal a GI phrase, farm-animal stupid!
Back to the point at hand.....
What possible reason is there to go to somewhere other than a medical center with a chamber? If you're bent then you are! You can take the O2 with you (and you should); if you have enough to get TO the chamber location, why would you go to a "regular" ER instead? What possible assistance can they provide, other than the same order to get into the chamber that you will get from a doc at the chamber site?
If you're having a suspected coronary event or something similar, then sure, an ER is fine. I understand the concept of stabilizing the life-threatening things first. But DCI-II is not a trivial matter, the damage it does can be permanent, and the longer you wait the more likely it will be. Intentionally imposing a wait by going to the wrong medical facility is just plain silly, especially when the evidence shows that most doctors have absolutely no clue when it comes to DCI and many of them will do things that will actually harm you.