Best way to combat vong tech is the pollen that the vong worked through several threads to make their tech immune to. The world itself has and breeds several large species including a leviathan breeding ground akin to Corbos. The noble houses that rebelled when the Republic had them rise up at the reinvasion of Alderaan have either been wiped out and the houses filled with pro one sith or is strictly controlled by fear because further rebellion doesn't kill them it kills everyone. The women, the children and the house servants. A rebel might be willing to throw away their lives, most are not willing to throw away the lives of those they are trying to save.
There are sithspawn being bred on the world as well which adds another element, the new queen that has been installed to the throne is heavy One Sith support for the betterment of her people with her coronation being the execution of several members of noble houses who might dislike it or even hinted at supporting the old queen. This world is a sith AAA world much like Coruscant and Csilla. A prolonged rebellion works in the favor of the people who can't just starve the houses, starve the enemy soldiers. Yes a rebellion can work, it won't be easy but it should be started with ground work and ways to counter the work that has been done.
Small attacks where you could fade away and not announce yourself were mentioned and a stronger method to rally support or shake the ones who are in fear of endangering their families into action. A straight attack makes it all work in One Sith favor with them needing to use the least amount of effort. Rebellion comes they can just blockade the planet,, burn or lockdown the food depots they control, leave the people to defend against hungry sith and vong spawn, let them deal with each other when there is no food in the stomachs. See how rebellious they are when their children are starving or soldiers demoralized trying to survive against constant attacks.
Sith can then make the offer of turning over rebels for execution for forgiveness and food, suddenly the world goes back to how it was before the rebels tried. Sith tactics don't have to involve direct combat when they can easily play to their strengths, when there has been little effort expended to undermine their development on the planet or their takeover. To quote a comic writer "You need to first establish a status quo to upset it." The freedom fighters haven't done anything to become a viable threat they are only just appearing and wanting to claim victory, they haven't made a reason to be considered dangerous meriting the sith to actively engage when they can just starve them out, can let the planets creatures itself kill them, can let the loyal houses turn them in or set them up into more traps to dwindle their numbers as the sith just sit back. Another way to look at this is freedom fighters invading force, Alderaan is currently Russia in the winter.
