Assuming that the ATF did get a second judge to weigh in, the answer to your question is very straightforward. The ATF lied to Judge B. Maybe Eric Holder will investigate and prosecute.
actually if the atf did do forum shopping when another court had jurisdiction, the information collected would be fruit of the poisonous tree.
remember there are 15 plus years of prosecutorial misconduct being withheld from the public.
Misconduct is SOP.