– Android is cheaper than Windows Phone (many phone makers pay Microsoft to be able to use patents used in Android, but even then, Android is cheaper than Windows Phone)
– Android has lower system requirements than Windows Phone
– Android has a thriving app market, Windows Phone doesn’t
Windows Phone low-end phones will only be hit if Microsoft convinces network operators to push them. That could happen if network operators were to regain power over the consumer by doing so. For instance, it could mean that on those phones, the app market is managed by the network operator, customers would pay different rates for different kinds of data, and customers could only use a pre-installed web browser that serves the network operator’s ads.
He just assumed that Windows Phone would have the same virus issues as Android.
This isn't to say it can't or hasn't happened on phones running factory stock roms, the Samsung /dev/exynos-mem permission bug on its own was one example of a huge attack vector on a limited set of Android phones, I just haven't seen or directly heard of it happening on a stock phone.
I hear later versions of Android did get smoother on flagship phones, but I don't know how or if that translates to lower-end devices.
Currently both the core team and OEMs are striving hard to work around it (reversing it would be impossible as it's baked in).
However, I think as mobile platforms increasingly take on the role of general purpose computers, it will actually end up being a net benefit, and Apple's decision will look as short-sighted as the lack of true multitasking in older Macs.
But maybe not? Who knows...
I agree with your points regarding limitations with Windows Phone. Just because an opportunity exists doesn't mean that they will succeed. Although I am unconvinced that the app market is that important. A few key apps are important, but Android app purchases lag heavily behind iPhone, and it is reasonable to suggest that feature phone users will lag even further (especially without a locally integrated payment system in developing markets).
Samsung and Apple both need to make money on their phones. Microsoft does not. Both Bing and Xbox were operated at a loss for years; it paid off for Xbox but not (yet?) for Bing.
But at the moment the feature phones and almost-smart phones by Nokia, i.e. the Asha series, are not running the Windows Phone OS, but the S40 OS (which is some kind of Symbian I believe).