The goal was to find out if the minion was killed at then end of the monologue, since the party has been invested in thinking that the minion was the BBEG.
Well that didn’t go as planned.
Edit: Apparently posting images is down at the moment, so had to troubleshoot.
Monologue implies that a second party isn’t necessary, just an audience.
Also I’d have had the BBEG either call in another minion or use Speak with the Dead or Revivify. What a fucking power move that would be. Man, I’m going to use that now.
Wow, I wish I had thought of that.
Great options. Alternatively, I would have had the BBEG just keep monologuing to the corpse without breaking stride. Maybe only realize the kill at the end of the speech as if the minions death was both accidental and irrelevant. (“Do you understand now?! … Oh. Yuck. Somebody clean this up!”)