My argument is as follows. You're right, and I'm appealing to a stronger Wolfram-esque version of Rice, together with the fact that humans readily throw non-essential goals under the bus in pursuit of speed.
* Building AI is a race against time, and in such races, victory is most easily achieved by those who can cut the most corners while still successfully producing the product.
* As a route to general AI, a neural architecture seems plausible. (Not at the current state-of-the-art, of course.)
* Neural networks (as they currently stand) are famously extremely hard to analyse: certainly we have no good reason to believe they're more easily analysed than a random arbitrary program.
* A team which is racing to make a neural-architecture AI has little incentive to even try to make their AI easy to analyse. Either it does the job or it doesn't. (Witness the current attempts to produce self-driving cars through deep learning.) Any further effort spent on making an easily-analysable AI is effort which is wasting time that another team is using just to build the damn thing.
* Therefore, absent a heroic effort to the contrary, the first AI will be a program which is as hard as a random arbitrary program to analyse. And, as much as I hate to appeal to Wolfram, he has abundantly shown that random arbitrary programs, even very simply-specified ones, tend to be hard to analyse in practice.
(My argument doesn't actually require a neural architecture of the AI; it's just a proxy for a general unanalyseable thing.)