I have many things I dislike about Apple, but I'm also a software developer and I know from hard experience that even the best testing strategies and the most stringent code reviews cannot catch EVERY bug. I'm in total agreement with this decision.
This is one of the problems with our world today. As soon as something goes wrong, there's a line of people waiting to accuse you of negligence and malice. It's a wonder anyone actually gets ahead in the world today.
Even if someone - a single person or a very small group - within Apple deliberately introduced a bug that could be misused, it's hardly fair to blame the entire corporation. To make a claim like this you'd have to be able to claim that Apple, as a company, deliberately and with full knowledge introduced and pushed a bug that allowed eavesdropping. And you'd also have to be able to say it was Apple's own decision (i.e. not because of government coercion). Even though I disagree with many of Apple's business practices, I can't believe the company would approve that willingly and knowingly.
We need to stop assuming everyone is out to get us, that everyone is deliberately acting against us. Sometimes mistakes are made. Sometimes you have to fix your mistake. But it's not fair to accuse anyone of malice when the fact is that it was just a mistake.
Of course, the problem with our legal system - and with any system for that matter - is that unless someone stupidly admitted in a recording or letter that they were acting maliciously, you cannot prove what was going through anyone's head.