IANAL, but I expect this is part of the prosecution's strategy from the start rather than a change.
My understanding is that lawyers like to use a multiple lines of attack/defense approach. So in the context of this case, they would first argue that object A is not of type B (and hence not afforded any protection that type B might confer), and next argue that even if A is of type B, that all type Bs are subject to prosecution anyway.
My guess is the next step of the prosecution's argument will be, even if A is of type B and type Bs are generally afforded protection from this type of prosecution, this case is an exemption because of "national security."
My understanding is that lawyers like to use a multiple lines of attack/defense approach. So in the context of this case, they would first argue that object A is not of type B (and hence not afforded any protection that type B might confer), and next argue that even if A is of type B, that all type Bs are subject to prosecution anyway.
My guess is the next step of the prosecution's argument will be, even if A is of type B and type Bs are generally afforded protection from this type of prosecution, this case is an exemption because of "national security."