Prosecutors will want to throw the book at the guy but they better be careful. The most they can get is possesion of bomb componets and manufacture.
All the guy has to prove is that he only meant to scare and made sure it could not explode, and he could beat other charges such as WMD production. All that legal stuff is probably a year from now.

Auto Zone is getting lots of free advertising as they are questioned by the FBI.
Good job all around getting the guy or conspirators.