Read that comment (https://news.ycombinator.com/item?id=7701017), it gives more insights on why it was "impossible" to get access to them.

I agree this should be a core principle: no access, no involvement. Except that when it has been decided not to give access to them, the company configuration prevented any action against the will of the CEO.

I should have resigned. This would have led to the resignation of the other engineers and the death of the project. I did not want that at first.