They mention in the stream that it was not going to be used today.

Pretty sure there was a call out late in the countdown regarding arming the FTS.

They armed the FTS, as they would need that if the range safety officer needed to do that. But it was not needed or used by the RSO.

Falcon 9 doesn't use an FTS manually triggered by an RSO. It uses an AFTS, which is controlled by the rocket itself.

My guess is it was armed for the early stages of the flight (when there was still a risk something could go seriously wrong and the rocket could start heading towards Orlandit), but it was disarmed (or just given very generous parameters) once the rocket was downrange a ways.

Based on what they said, I'm assuming that it would have been triggered at some point before it started coming down, but they were expecting that it would be destroyed before that happened.

The upper stage hit the ocean intact. That suggests the FTS was not triggered (or it was triggered and failed to destroy the stage, which would be more concerning)

I suspect they'll still log when it would have happened so they can confirm it was working properly. That would be interesting to hear about.

Do they actually go around collecting all of the various parts that fall back into the ocean? I imagine that's a huge amount of debris.