Stick rebound and shock transfer are two different things.
You're correct, they are two different thing by themselves, but you might not realize they're directly related when it comes to drumsticks.
While I would have to buy a pair and cut them up to be sure, there is a black plug at the butt of the stick. This plug is more than likely a rod like insert that goes partway into the stick itself. The insert is what absorbs the shock, not the stick. The stick would perform as usual, but when the vibrations (they travel as waves that start at the point of impact, the tip if you are doing it right) travel down the shaft of the stick, the insert will arrest, or capture if you will, the vibrations.
OK, now I see for sure you don't realize it.
In regards to the ZILDJIAN ANTIVIBES
, I've played them extensively when they first came out and yes they do work, if/when you do play them you'll realize rebound is affected and it should be obvious as to why.
The 'insert' in the ANTIVIBES doesn't absorb the shock, it acts as an arrestor, it interferes with the vibration. 'Shock' is energy in the stick which has been produced by impact, that same energy propels rebound.