Going nowhere
This scumbag individual is going nowhere. Ecuador are highly unlikely to give him up now. UK police are not going in after him. He's unlikely to leave the building because at some point he will have to touch UK soil and then plod will have him. Ecuador can't currently make him a diplomat, because he's not Ecuadoran. He can't come out in a diplomatic bag because he's not a document.
There will have to be some fundamental change in the law, or someone will have to back down and eat some mahoosive humble pie before this toerag goes anywhere.
(Useful, if slightly old, background here.)