That's a good point. But there was an article in the BBC that stated at least one agency in the UK was aware of the situation. Given that the guy is temporarily at least a hero, the short time frame since Alphabay was taken down and the evidence discovered, and the fact he was traveling to the US, it was probably better for everybody that it happened in the US. I don't think politicians in the UK would have enjoyed the prospect of extraditing him to the US. My impression is not that they were sitting on this for a couple years, but that the Alphabay operation unveiled a lot of info that they couldn't act on until it was finished. But that's all pure speculation on my part.