* The Nexus devices (during lifetime, usually 1 year less than iPhones) are patched sooner and more often than iOS.
* Google Play Services shouldn't be able to patch system libraries or the kernel, that would be a security issue. Patching those is what a system update is for.
* Nexus devices have (IMO) much better "enterprise-grade" software support than iOS, whatever that means. And it's only set to be better with N. [1]
[1] http://www.techrepublic.com/article/three-important-security...
The oldest phone to officially get Android 7: Nexus 5, released in Oct 2013.
Sure, it's 1 year less, but you sure did exaggerate. Also Nexus phones get more frequent updates than iPhones, and I'd argue they're much better updates.
[1] https://android.googlesource.com/device/lge/hammerhead/+/and...