If the thread was titled "I'm planning an 85m dive, what gas should I use?" then I'd be very interested in discussing these points. But it was planned as a deep air dive (or rather series of dives)
I'm not saying your points aren't worthy of discussion, or that you shouldn't discuss them, just that I don't see them as relevant in this instance. It's not like I sat down and said hmm, I think I'll choose to use air instead of any other gas for this dive because I think it's the best option
You don't always need "the best", sometimes adequate will suffice