Windows phone is indeed a much safer OS for the moment. Security by obscurity. It worked for OSX for quite some time in the 90s and early 2000s :)
Because Google is not available in China, so most of Android developers in big companies know how to cross the GFW, after crossing the CDN of Google will make the download very fast. So I think Android apps may be less effected under this situation.
wrong most of the time Google is accessible in China, different from several years ago
This scheme isn't needed with Android since most devices are vulnerable to well known exploits.