Silicone is really tough to get rid of, when I worked in an auto paint shop we'd curse the owners who used silicone products because it was so hard to remove, even with sanding. I'd toss the pads then try auto brake cleaner like CRC Brakleen on the rotors, followed by very hot water with Dawn liquid and a hot water rinse.
Edit: We used Prep-Sol prior to painting, it claims to remove silicone (kinda does) but is costly:
https://www.merrittsupply.com/produc...3919s-solvent/