That's a good point, but then it is an odd thing for them to care about the fuel savings vs. their claim of not needing the first stage and allowing for single stage to orbit with a plane type launcher, which is a far bigger deal in terms of cost savings.

E.g. consider that Musk a few years ago estimated the fuel and oxidizer costs for a Falcon 9 v1 at ca $200k per launch, with a list price for the launches at $54m to $59.5m. Cutting the cost of the rockets themselves on the other hand, whether by reuse or making them smaller/cheaper will matter much more.

I guess whether eliminating the first stage entirely vs. reuse will matter much will depend on how many times recovered stages can be reused and how much it will cost to prepare them for reuse, as the potential fuel savings are basically rounding errors.

Exactly. Another way to say this is that this launch requires less Delta V. It's completely different than getting cheaper fuel of the same mass (which would be trivial).

smaller light rockets with a huge tower attached to it