...Because the only functional difference between dero and this hypothetical is that the unknown entity is captain, so it comes down 100% to your trust in him, not in the code, not in the blockchain, not in anything else.
And the only way to change that, is to verify all the code (which as I have also pointed out, does not even suffice entirely, as you are still trusting that the code you see is what was actually running).
The way I read this is that even given the source code you still wouldn't trust that the binaries it produced are the same as the existing compiled binaries* so I am forced to conclude that nothing will satisfy you.
* - because apparently the golang compiler does not create bit-identical output when run on different machines despite bit-identical sources.