Another possibility is that Rashi is learning that bein adom l’Mokom is somehow a way of learning how to better be mekayem bein adom l’chaveiro.
If you start from lashon acher and read through the Rashis then “????. ??? ???? ????” is saying all the mitzvos bein adom l’makom are commentary on bein adom l’chaveiro.
I’d probably have to be a big ba’al mussar to understand what that really means but it would solve the issue you find unsettling.