The tweet is FUD... He missed the most important part.. How do you install this on a Droid or most other Android devices? You need to root it just like you do to jailbreak a iPhone.
Android devices are far from open.. Don't believe the hype... My hope is for a Ubuntu tablet.. Maybe that will actually be open...
Isn't your argument flawed though? Apple vertically monopolizes the entirety of the platform by dictating hardware, software, and subsequently content to some degree. Droid phones need to be rooted because of additional software phone companies place on these devices to prevent their "bloatware" from being removed. While Droid based phones may be "far from open" the culture promoted by Google, is quite the opposite from the culture imposed by Apple. Conceptually the tweet is accurate, in practice not so much. I feel like the arguments being pushed by Jobs are trying to point out what's wrong with Droid, but they are somewhat out of context, because at the level Jobs is advocating it's really Apple vs. Phone companies and not Apple vs. Google.
You can tune a piano, but you can't tuna fish. You can tune a filesystem, but you can't tuna fish. -- from the tunefs(8) man page