..all the exercise-and-hold transactions were quite old...the most recent was in February 2024...
There haven't been more recent exercise-and-hold transactions because all of the options are underwater!
...one would expect heavy [open-market] buying in the recent prices. Unless, of course, there are M&A discussions that prevent them from doing that (one hopes).
Exactly right. The beauty of exercise-and-hold transactions is that insiders are permitted to execute these transactions even when they have material non-public information. So, we might well be seeing exercise-and-hold transactions right now if the options were not underwater.