Apple propagandists have a way of acknowledging the wrongs of Apple while telling readers to not use Google's products and services:
Google says they like open things. Google had "Don't be evil" as a motto. However, Google does things that aren't open and things that are evil. That is why you shouldn't use Google's stuff.
My strawman isn't perfect, but it gets the gist of what Gruber, Marco et al say: Google tries to present itself as a better company, but they're not, so don't do business with them.
It's a noble point, but it completely glosses over Apple's equally bad behavior under the excuse that Apple, unlike Google, never pretended to be nice.
And it tries to force the conversation into a binary discussion: Apple vs. Google, iOS vs. Android which it isn't. The OP is basically the same as most of these kinds of things "<insert potentially meaningful issue>, google is bad for this issue, Apple is free from this critique" which is trite and tiresome.
I've noticed a significant decrease in Daring Fireball posts hitting the front page in recent months, is Gruber now the new Apple shill^H^H^H^H^Hevangelist we have to deal with on HN now?
The only interesting point he makes here is that users shouldn't monoculture their services -- which I think is a good point. Then he proceeds to undermine his own argument.
I bet there are millions of Android users who'd love to use iTunes on their latest Android phone, or some other company's service, but Apple itself is responsible for not rolling these services out beyond their hardware ecosystem (acknowledging the incredibly shitty Windows ports of iTunes), thus preventing non-Apple users from become users of components of Apple's services.
But as it stands, Apple is not a good supporter of Marco's own arguments. In fact, if I don't want to use either company's services, I bet I can use more on my Android device. Hell I can even run my own mail server on my Android phone with half a dozen screen presses if I want to.