Maybe, but rubber couldn't get any harder than brass!
The point is that rubber bedding can change. The cushy bedding you sighted in your rifle in summer could change POI under the cold of winter.
Every once in a while, a gun writer will publish an article on bedding with silicone sealant for some of the same reasons as mentioned above for rubber. For some reason, the practice has never becomes popular.
Do it. Report back after a year of experience. You may be on to something.
