Yes this acceptance of some aspects of religious practice and rejection of others is highly interesting.
It seems to me they were working had toward a coherent and consistent system that would have totally reformed religion but grounded it in the benefit that comes from venerating the sage (VS43 on the veneration helping the generator) and having a goal to work toward (the lifestyle of the gods) while also making sure that it was not seen as a totally fictional "platonic noble lie" by linking them to our expectations of higher and lower life in other parts of the universe.
It's definitely not "atheism" as people generally define the word today, bit it is strictly non-supernatural.
I too can see the benefits of such an approach, especially in combatting the nihilism that is so damaging to so many people. I see this as much more effective than Nietsche's eternal recurrence.