Can't see human rights coming into it. His rights are not general, but specific to one granted political asylum. If he steps outside the Embassy, he will be arrested. His reason for so doing is immaterial. And he should be arrested. He should not have been granted political asylum in the first place; there are no valid grounds for thinking he is a true victim of political persecution; but, once he's in the Embassy, on any grounds, and is allowed to remain, we will not enter to arrest him.
Can't they just smuggle him out in the boot of a car and onto a private plane?
No-one would ever know. When the police asked where he was because they hadn't seen him for months, the Ecuadorians could just say 'Hmmm, come to think of it neither have we'.
Surely the assurances have been given by the government, as indicated within the question; namely by saying that "it would not prevent any medical care that he requires."
However, that in no way should prevent his arrest as soon as he leaves the embassy. Criminals are afforded medical treatment all the time in or outside prisons, often with a police guard in attendance in the latter circumstance.
An Ecuadorian official said they would be happy to keep him in the embassy (quote) "for two centuries." I'm perfectly happy with that; it doesn't much matter to me where he is banged up! All he has to do, if he requires hospital treatment is come out and get it.
Same old story , if all else fails try the medical scam .
Ronnie Biggs , General Pinoche, Lockerbie Bomber, MPs facing fiddling expences, Abu Hamza , and if that doesn't work there is always HR .
Following their release with the help of their God they all recover.