FMLA is not just something you can request like a sabbatical. There are specific reasons and looking for excuses to goldbrick is not one of them.
The fact this snowflake has asked in the past will work against it.
I wonder the caliber of gun held to its head to keep it in this "toxic job." Those of us with SKILLS and ABILITY would never stay in such a terrible situation.
I know this type of EE very well. Uses up sick and vacation leave as fast as they accrue it, clock watcher, grumbler, always offended. Just this side of insubordinate. Hard to fire in a large organization as they know every little tiny rule.
The org will be will rid of it.