You can’t force a developer to become a coin holder like any other.
You can just give developers coins outright, in which case they’re free to just sell them right away (which investment theory say they rationally ought to, in order to diversify away from their employment-induced exposure to the cryptocurrencies market).
Or you can give them future rights to coins many months/years ahead, or time-locked equity in a coins fund, or some other mechanism you’d come up with. In which case they can’t sell their coins and thus are not in the same situation as other coin holders and are not perfectly aligned the way you phrase it.
Moreover, you’re completely ignoring the other incentives that ZEC coinholders have: the whilesblower, the dissident, the person of “wrong” religion or “wrong” sexual orientation, trying to protect their financial transactions — are they in it for the “upside” of long-term capital gain?
So you can discuss the virtues of this inevitable misalignment, but calling it simple and perfect is just not true.
In any case, so far you’ve said nothing about the amount of coins needed to “become part of the tribe”. It seems pretty arbitrary to decree that it must be a constant amount of coins per month, and that anything else is a horrible “artificially bind” that “chokes ECC”.
(Not to mention that even constant-coins-per-month is possible, with some planning and within some range of parameters, as @acityinohio pointed out above. I was wrong when I said earlier that it’s impossible.)