I agree. The limit should be the same.
However I did fly on a coast guard helicopter carrying a diver to the deco chamber and the pilot told md he was not allowed to exceed 3000 feet, as the cabin was not pressurised.
Of course a quite different situation...
As you note, a very different situation. One someone is actively sick with suspected DCS, the other someone is trying to minimize the possibility as practically as they can within their travel/vacation time allowance.