I'm not sure "it's open, once it's obsolete" is how the philosophy is intended to work.
Also, Carmack doesn't engage in PR wars about the non-openness of others.
I think the difference between Carmack and Google is that Carmack writes proprietary software and then releases the source code when it stops selling. Google on the other hand is writing open source software but is choosing to hold back on releasing the source code ... why?
id isn't trying to create a hardware ecosystem.
Google created a hardware ecosystem with a variety of partners. If they start playing favorites with who gets new Android releases, they will undermine that ecosystem.
It's not so much that they're keeping the code closed, it's that they're only releasing the code to a handful of select partners. All the small players get left out in the cold.
For example, John Carmack/id Software don't release their current engines until they've made progress on the next, better version. I don't think many people consider Carmack to be evil or non-altruistic.