He made the post looking for a developer 9 months later, on October 11, 2011.
And as I mentioned below, the fake ID issue seems to have come up after the email warrant was issued, so it wasn't a factor there.
which was apparently the first mention. So, as far as the agent could tell, this was the first person to mention Silk Road on the open Internet. That's what's reasonable.
(Also, from a pure Bayesian POV, the fact that it nailed DPR on the very first try goes a lot towards demonstrating its relevance. NB: this parenthetical is not a legal argument; otherwise you could justify any search that turns up evidence.)
Anyway, my answer was that if the police really had such strong suspicion of someone and they were right, they've got to have enough to get a warrant anyway, which is similar to what you're saying.