This is beside the point. Gravity moves at the speed of light. This is a very basic and well understood fact in particle physics.
Discussion
To me it seems more and more like an assumption that everyone just makes.
The speed of light pops out of Maxwell's equations as the inverse square root of the permittivity and permeability of free space. G doesn't come into it. Invariance with respect to reference frame *is* an assumption, but one that fits observation.
Bitcoin told him that he must be right
yes you must be right. if sun all of a sudden disappeared, we wouldn't feel the lack of gravity before we actually see the disappearance. it must be at the same time
perhaps more relatable example would be supernova