There seems to be a relatively simple way to deal with this.
Get Sweden to give a legally binding undertaking that they will not extradite him to USA or any other country if UK extradite him to Sweden to stand trail. And if he is acquitted on the sex charges that he will be free to go where he wants.
As for the UK suspending Ecuador’s diplomatic status, so they can enter the embassy and arrest him, I believe that would establish a very dangerous precedent for countries worldwide to do the same and ignore diplomatic rights. Just image how the USA would have reacted had the Chinese done that when in May the blind activist was in their embassy in China.