On Sunday, January 27, 2019 at 3:39:57 AM UTC-7, Quadibloc wrote:

His complaint is that Newton is expressing the truth given us by Copernicus in
an invalid way, because he drags in an "imaginary observer".

Basically, his position could be stated as "Reference frames considered harmful",
presumably because he doesn't understand them. So he is a Copernican, but he
limits the ways in which Copernicanism can be legitimately explained.

John Savard