the disconnected mic, and broadcasting into a fist — "Troeltsch, left eye ominously nystagmic, pretended…"

The disconnected-headset gag pays off: Troeltsch's dead microphone is stolen "to the rejoicing of all," and he simply carries on broadcasting into his fist, addressing "a subscription audience" that does not exist through a mic that was never plugged in and is now gone. The equipment was always beside the point — the compulsion is to transmit, receiver or no — so the confiscated apparatus changes nothing, the address-into-the-void needing no hardware at all.