It is definitely enough to have CBP flag any packages crossing the border that are associated with that name, for which no warrant is required. After that, well, I'm no lawyer, but I think intercepting a package full of fake IDs is enough to justify a broader criminal investigation.

Alone, no. Read the 10 pages of corroborating evidence following these initial steps and there's definitely enough for a warrant.

A warrant for search and seizure of his computers and everything in his apartment? Probably not.

A warrant to keep "pulling the string", issuing subpoenas, and compelling production of evidence from those who might have it? Absolutely!

What is the cut off for using pseudonyms on obtaining a warrant?

I assumed bitcointalk had a small member base when "altoid" joined. A quick look at their tables show 3,694 total new registered users through January 2011.

"altoid" registered on shroomery on January 27th 2011 and the "altoid" who revealed his name publicly registered on bitcointalk on January 29th 2011.

It's definitely enough to ask Google, and possibly his bank or credit card company (to see if he bought any servers recently).

adorable.