I give Apple props for for their contributions to LLVM or WebKit (and OpenCL, and Darwin), no one is saying they haven't done any good things for the ecosystem, but that doesn't erase the egregious damage that the iOS T&C impose on the ability of people to do what they want with their devices. To me, that ranks them lower. That, and the aggressive "thermonuclear" offensive litigiousness they have, not just on patents, but even going back to the Look-and-Feel lawsuit of the 90s. I'm an Apple fan boy when it comes to their hardware, I've owned every Apple device, I own an iPhone 5S, the A7 is remarkable. I love the hardware, I hate the closed nature of the platform, the fact that I need to jailbreak my device to have ownership of it.
For the average consumer, control of "the next big advertising platform" is a meaningless abstraction, it matters to people in the ad buying business, not consumers who generally don't like ads in the first place, and tolerate them mostly to get free stuff. And how does Android "control" mobile web advertising anyway?
But for the average consumer, telling them they can't install App X on their device that they spent $300 on because Apple censors don't like it is much more direct.
No company is perfect, but I can say as a Googler, your cynicism is basically wrong, that open source isn't just a marketing tactic, but that the rank and file at the lowest levels of the company, culturally believe in it. Google has disappointed in the past on the degree of openness, and there is much to improve, so I am not uncritical of it in this regard, but if you were to query the rank of file of Microsoft and Apple with regards to open source, and Googlers, you'd find a lot more zealots at Google.
The world isn't black and white, it's shades of gray, and some are just a much brighter shade of gray than others.