unless you are contemplating on using DOT5 (silicone) fluid, otherwise: using silicone grease during the assembling of caliper piston seal is a big no-no, citing glycol brake fluid contamination issues.
Also: using brake fluid as lubricant while installing caliper piston seal is okay if and only if it(the caliper) gets put into surface right-away. Glycol based brake fluid is hydroscopic (water-affinity, or water-luving), so extended sitting around after assembly would do more harm than good.
I have long been using a brake assembly grease called PBS brake grease, made in Australia ...100% compatible with rubber parts and glycol based brake fluid.
Been using PBS for over 2+decades now, zero returns due to assembly errors or rubber seal swelling/failure due to lubricant issues.
I don't use any Syl-glide for I have never been able to confirm it's compatibility with glycol based brake fluid.
Q.