You are right. Also, if you look at the ingredients on the can of silicon spray, it is mostly hydrocarbon solvent as well.

However, if squeeky rubber bushings are driving you crazy (mine have squeeked during the rainy season almost every year since my car was new) you don't care too much if you shorten their life, so long as you can quiet them. I use silicon spray. Usually takes two or three treatments, and a few rainy days washes it back out so the squeek starts again.