I understand that you can't collect a payout if you don't commit a player to a tournament or a highlight. And if a highlight has only one team commited, and the other side is empty, the commited team takes all 3 payouts.

But what if on the last move (so they couldn't commit another player) the player gets injured and that clears out the one side of the highlight (or the team from a tournament). Or this could also happen if one team has all of their players ejected (from one of the highlights or tournaments) via being caught cheating.

Because the coach had commited a player prior to the scoreboard phase, do they still get the basic team payout for the highlight or "Lose" payout if in a tournament?

No, you still have to have a presence during the Scoreboard Phase. That's why ejections from cheating can swing things, never a good idea to have only 1 player with cheating in a zone/tournament. Cheating ejections happen before Determine Winner, which is followed by Collect Payouts.