I have to respectfully disagree. The man was a seasoned veteran of both Chinese law enforcement and the Chinese political milieu, and for him to go to the US embassy must have been a very calculated decision considering the stakes at hand were, for him, potentially life or death. Furthermore, looking at the British Government and it's actions over the last decade and a half (one instance being the circumstances in which Royal Navy sailors were captured by the Iranians a few years back, and in particular British gov response to that capture) I would say that the chances of the British whisking him away to safety must have been substantially less than that of the Americans. The man made a good call, it is just that the odds were not with him that day.
It may be said that American influence with the Chinese has waned, but it is still greater than that of any other country (and far greater than that of Britain). If the US chose not to save him the British Government would not have done any better - they may actually have given an apology on top. I'd flee to a French embassy before a British one, although with Sarkozy possibly being kicked out even that option may not work for long. The US embassy, in a Chinese situation, is possibly the only embassy in China the Chinese authorities respect.
Problem is, he had no chance of being saved by the Obama White House 7 months before the elections. They aren’t going to risk a dust-up with the Chinese, especially now.
I think he had a chance of being brought to England for further questioning, had he divulged some of his story and made the rest of it dependent upon exiting China.
Obama should have turned him over to the Brits instead of putting him back on the streets.