Says anyone who cares about the safety of people using the airspace.  That's what transponders are for.  What kinds of activities would one be doing with their transponders turned off?  How long would a transponder-less spy craft be permitted to buzz around over the U.S. before it was neutralized (assuming it wasn't part of a self-inflicted false-flag operation like 9/11?)

Some people we know in that region are totally cool with switching off their transponders and hiding behind U.S. aircraft, Russian aircraft, and general civilian aircraft in order to get into position to launch an attack.  Some people consider that to be a cowardly tactic which puts innocent lives at risk while the perps seem to feel that it is a demonstration of their superior intellect.  They think, I guess, that nobody else would be 'smart' enough to think of such a thing.