They meet these metrics while they are under formal process just before termination. I used to work with a couple people clearly working multiple jobs who switched focus when they were PIPed.
If they are refocused on their job and now meeting metrics why terminate them? People can become unfocused for a variety of reasons beyond working other jobs. Life happens. If they don't remain focused and again don't meet metrics they have already been given an opportunity and should then be terminated.