I always put a very thin coat of copper grease on the mating surfaces and also on the mating surface between the rotor and the alloy wheel.
Only a small amount is needed and you want to make sure that there isn’t too much that can run onto the rotor friction area even when hot.
I use High temp anti-seize compound, Nickel compounds are best but more expensive than copper, which will do in your case unless it is turbocharged, then use Pure Nickel compound.
If the dealer has measured them, even though most of the corrosion has now gone, they may be too thin and need replacing.
Given rotors are cheaper than the consequences of brakes failing, I would put the news ones on. And have just done so on all 4 corners of my car.
Here, check this out,
I'm going to be rattle canning my truck, I've done this before. I came across a great DIY video by ChrisFix on YouTube. Here is link to the video: https://youtu.be/vUdSUDObwVc , check out 12 minutes into the video, Chris talks about hiding "hard lines" even if just wanting to paint a small section ...