I think they were referring to reverting the work of the employee that left that put the organization in a bind, not someone still on the team.

I had the same thought—revert the changes to get the rest of the team back on track. The problem could be that the changes could be over the course of many commits, so rolling back is complicated and almost as difficult as moving forward.

Yep multiple commits over a long period of time + different services (microservices).

Was possible to revert, but the work needed to be done. The biggest mistake was letting this singular person take control and not let anyone else in on it. Reverting would have been a big effort as well.

That’s only if you don’t discuss it first.

Well intentioned work can still be bad or not usable or not the thing the code needs right now.

If they're still around sure, but the engineer in this case had left and wasn't around to maintain the work anymore