Ultimately, if push came to shove, Primary arms should have something listed pertaining to "secondary vendors" in thier written warranty, which looking at it right now, doesn't mention anything about where you bought their product from.
Looking at the actual unit and the box it came it, compared to the invoice, there looks to be a serial number associated with the unit. Worst case, IMO it would be Primary Arms responsibility to trace the unit's point of origin per retail sale and then deal with distribution if they have an issue on how I purchased it (after they take care my issue).
As a consumer, I believe my expectactions aren't that high, just would like this unit replaced due to the circumstances with the unit, which I went out of my way to document so I don't come across as a crazed lunatic LOL
Worst case, it's nothing but a good business practice due to the circumstances to just take care of the issue first since there is something apparently very wrong with the red dot which was sold as new in the box.