Dark trooper Moff Gideon lead does not work against General Grievous.
Dark trooper Moff Gideon's leader ability states:
It does not say "excluding droid enemies." Meaning that any time General Grievous (or any droid enemy) gains 2% turn meter (or any amount) they would then lose 8%, making a TM loop impossible under these conditions.
However, in practice you will find easily replicatable results showing no droids lose turn meter at all despite the leader not having any exceptions for them. Having just lost a GAC round as a direct result of this, I have returned to DTMG's leader ability code to find this:
This line is the hidden mechanic preventing the turn meter reduction. My best guess is that since DTMG lead cuts out droid imperial remnant allies (Dark trooper), the team added non-droid clauses all over and accidentally put one here as well. If it was intended to never impact droids, at the very least that text needs to be in the lead. It would have saved me 900 crystals today, and anybody reading the leader is at risk of being clearly mislead by what the ability does as I was.