I don't know of any clear distinction in the rules.
There isn't a clear distinction because the gun doesn't need the smartgun system to be vulnerable to bricking in the first place - throwbacks aside, any and every gun can be wireless and can be bricked.
Yep yep yep.
"Wireless:The weapon displays an ARO that tells you
ammo levels and ammo type loaded. If you have a DNI,
you get two additional benefits. First, ejecting a clip (for
weapons that have them) is a Free Action rather than a
Simple Action. Second, changing fire modes (on mod-els that have more than one) is a Free Action rather than
a Simple Action."
This is the wireless function all firearms have. So all firearms can be wireless on / off. If they're on, they can be bricked.
And I think if they're off they can't be bricked.
I guess it can get problematic if you have the external smartlink on but the gun itself off? Maybe that's impossible.