The important question is if you think it's possible to create impervious functions of ~100 lines of code. I tend to think that with modern formal verification systems this is a feasible goal. Otherwise you have to stick with closed-source security-through-obscurity and rely on legal reversal. This seems pretty weak to me, though - ex, if a stock exchange was hacked, sure you could reverse it legally, but the market disruption would take years to recover. Regardless of the specific nature of crypto, I think formally verifiable open systems are both achievable and a worthwhile goal.