As a dealer technician, we used roloc discs on aluminum all the time,
I learned about the surface conditioning discs at the Chevy dealership I was a service advisor for. The guys used a LOT of them, on everything.
I started using them when I moved to an independent shop, and on my own projects.
but you definitely need to be careful about which abrasiveness you use. If you use a brown roloc on aluminum, you're going to destroy your piece.
Brown was all I ever saw used, or saw for sale. Didn't know there were other colors until after I quit using them.
As said--GM specifically warns against their use. The abrasive material goes everywhere, including into the stalls next to the one where the disc is being used. Looking back on the situation, I think I know why there were so many problems with the transmissions that the Dealership overhauled. The guys would pull the valve bodies apart, and they'd cover 'em with shop rags, but while they were working on 'em, the guy in the stall next to them would be cleaning gasket surfaces with the "cookies". So the oily valve bodies had all sorts of abrasive dust dumped onto them.
I quit using them when the local machinist warned me against them. He said that gasket surfaces became "wavy", moreso on aluminum but even iron surfaces were affected. He could see the "waves" as the machine resurfaced the parts--the apparent depth of the cut would vary with the amount of material removed by the abrasive discs.
Eventually, I bought a couple of the "finger" style, but decades later, I've never actually used 'em. There's a couple in my tool box growing beards and using canes, they've never been used. I went back to scraping instead of abrading.