I don't think Google cares about it as a web standard. They just want to deploy it widely through chrome, ChromeOS, and chrome on Android (eventually), and use it as a Trojan horse for their own binary applications and OS components.
I don't follow the trojan horse logic since they already have the unfettered ability to ship any binary component they want to the platforms you list without using Native Client.
You're right that Apple won't allow that on iOS, but I don't think they care. This is about them establishing a new platform to displace Android and the open web.