This fight is a little difference, for one they won't appear in the tournament because they are simply too powerful, and secondly its the grand finally - so I thought I'd up the anti here. And besides, in the scale of things - how promiment is a few Moffs in comparison to the galaxies greatest Sith Lords?
We also need to really consider the importance of having a sith army - Sidious has few if any weapons to defend against the full might of a Sith - apart from himself and sheer firepower.
EDIT: People have mentioned Dark Troopers, Shadow Guard, etc. but how do they match up in terms of numbers and power?
The number of Guardsmen are unknown, but speculated to be less then fifty to tens of thousands, but at any one point were estimated to be at 400. This is just the regular Royal Guard however, the exact numbers for the specialized variants are unknown but I guess if we take from what is said of the Royal Guard we could try and estimate, though it would be an estimation of...well an estimation.
The Dark Trooper is the same way.