Buried in the article below the clever though not original point that encryption is not math, is a much more important point: This debate should really be about whether or not people have the right to have secrets. If your answer is "no" then you ought to explain how you square that with the fact that many of our everyday activities can be considered criminal in some jurisdictions.
Is the position "people have the right to have secrets, but companies don't have the right to help them" coherent (not saying I endorse it)? We already accept that phone companies can (be forced to) allow wiretapping with a warrant. They aren't allowed to prevent the government from wiretapping. So why would a company be permitted to sell devices with encryption? You also need to weaken "allowed to have secrets" to "…
Then as many have pointed out, that these devices are becoming extensions of our minds.
So I can see those companies thinking that they have a corporate responsibility to protect their users. Especially if not doing so puts their users in danger.
I don't assume that freedom loving countries like the US are the only countries where warrants are issued. Some warrants are issued in other countries, some of them with oppressive laws, and device makers need to think about users in those countries as well, not just about US users.
A somewhat scary discussion, but one that we might see sometime, would be is there some kind of metric we can apply to governments to see whether their judicial process is up to snuff in terms of protection of rights, where we then create systems that respect only those warrants from jurisdictions that meet a standard of rights protection. In other words build into whatever solution a recognition that not all warrants are created equal.
Not that this would surmount the security issues of having a backdoor that could be hacked. That's such a devastating flaw in the anti-Apple side that I'm not sure it can be overcome without the help of blinders.