Obviously, we don't know what happened there.
"It has never even occurred to me that a player could be baited by an umpire targetting him for ejection. I guess I am just naive." Yup, you are naive to certain kinds/types of umpires.
"I guess what I am asking is this: Is it ever appropriate to bait a player or a coach to get him or her tossed? I would think not." I agree. There is no need to help a participant eject himself. And the vast majority of them will do just that, eject themselves.
"Have you ever seen or heard of it happening?" Yup, lots of times - primarily by those working the little ball game, once by a softball ump, and a number of times by basketball folks. I don't do basketball, so ...
I have told the baseball guys and the softball guy that the first time they do that in a game I'm working with them, that will be the last game we work together.
In adult ball, I am a strong believer in the "FU" call. Used properly, it is a very effective tool. But, that's in response to a player's inappropriate action. For me, or another umpire, to take the inappropriate action of starting the confrontation would be wrong. For an umpire to bait a player, or even "chirp" at a player about a poor play (but wouldn't we all just love to chirp about "...way to kick that one short, you just cost your team the lead."
) - that would be wrong.