Yep... a microphone is never turned off unless it has a switch on it and you flip the switch off. Otherwise it is broadcasting somewhere. Either the guys in the booth hear it... or the public hears it.
I agree, this arguement is on the order of 'I didn't think the gun was loaded'.
Regardless of whether or not it was an accident, his comments were pretty over the top. I enjoy listening to Savage every now and again, but I can't take very much of him because he has no concept of self control.