They weren't lock picking they were just putting miscellaneous bits of metal in his door lock.
That's very much the point. The FBI can make an argument that they weren't trying to gain access (since a real attempt to gain access would have looked different from "entering miscellaneous strings"). They were trying to see what the system did when authorization attempts failed. As far as I know, there's no law against that. It's similar to going through a suspect's trash.
If they weren't trying to gain access, what were they trying to do? Buy drugs? I don't buy the trash analogy.
Umm... since when is guessing passwords not an attempt to gain access?