I've never heard the term "unresponsive" in any other capacity than in a medical situation where the passenger isn't responding to any sort of stimuli. If it's some sort of "security" term I've never heard it or seen it used. If the only thing the OP did was not reply when welcomed on board I am equally as confused. Heck, if I had everyone removed that didn't reply to my greeting then I would be flying around on empty airplanes. Even if a passenger was in the exit row and refused to acknowledge the briefing then I would just move them out of the exit row but not remove them from the flight (unless there were other problems with them).
The crew should be filling out a report for removing a passenger, but it can be submitted up to 48 hours after termination of the trip.
Hope the OP follows up with what's happening.