My limited knowledge of silicone lubricants is that they are water resistant and good in some applications. However, they have low film strength and so are not suited for significant loads. They get squeezed out. They can be good for electrical contacts, since the exclude oxygen but let the contacts, well, make contact. My knowledge is 10 years old, and maybe some of the silicone greases have additives that make me wrong.
Please put me back on the right path if I am wrong.