To answer your rhetorical question: No, rolling out a product with such severe bugs is certainly not the brightest idea.

I don't want to criticize your organization, but if I had to distribute a game to thousands of customers, I'd consider testing it before, on several PCs. And when changing an essential setting such as the nexus, better read before what the manual says and recommends about it.

Ok, what can we do now that the damage is done? Your FAQ list is ok at least. But you can't distribute a game with a nexus 500 setting. An update would help, but not much. Using A7 instead of A6 reduces the nexus requirement by maybe 20%, if at all. That's probably not enough to fix your game. Another advantage of A7 is that if the nexus is too small, the memory is automatically allocated from the heap. This does not reduce the overall memory requirement, but prevents "nexus too small" warnings.

The real fix is reducing the textures or whatever it is that fills your 500 MB. Or else, distribute a RAM expansion together with your game.