I understand there is at least another door, plus of course you have to keep an eye on roofs and so on.

Perhaps they suspected an escape or extradition attempt with a well-funded commando-style raid?

I don't think that Sweden will storm a foreign embassy in a foreign country non the least, and if the US wanted him that bad they would've gotten him already.

The guard most likely wasn't to keep him safe, but to keep him in the embassy at all time, this is the same kind of guard that a US diplomat would've gotten while visiting the USSR and probably still gets when they visit Russia and vice versa.

The US wants him badly. It insinuates the rape allegations were to get him extradited to Sweden where he would then be extradited to the US.

I think we have different definitions of what "badly" means when we are talking about the full might of the United States, if they wanted him badly Cathryn would've been making zero-dark-frothy by now. Also the rape charges pre-date most of the embarrassing leaks on Wikileaks, not to mention that a trial in Sweden of all countries is not the place you threaten some one with, and the US-Swedish extradition treaty makes it unlikely for that to ever happen.

And most importantly he's been held up in the Ecuadorian embassy not the Russian one, Ecuador is the 4th largest receiver of US Economic and Military aid in South America the US also provides loan guarantees for most of Ecuadors loans including the recent 10bln USD loan from China which was secured through the IIC which is a US body.

The US isn't going to go assassinate a high profile world famous journalist. Everyone would suspect them.

It would be an enormous risk and an even bigger disaster of international diplomacy to kill an Australian without trial. Grow up.

You have to custodiet all the ipsos custodes.