This isn't just an interesting move, it was probably the only way the TextMate 2 story could end, apart from the whole project—and TextMate's six-year legacy as the first great OS X-native editor—being abandoned and dying out. Though, as Marco Arment points out, this is more or less the same thing. TextMate development can now continue at whatever glacial pace Allan Odgaard likes, and he can refer anyone who wants to know about progress to the public commit log on the GitHub project page rather than just dropping cryptic updates on a mailing list once every two years. It's even possible that open-sourcing TextMate, and giving users/hackers more visibility into what the heck he's doing, will give Odgaard a better feedback loop and more incentive to actually ship something people can use. (To be sure, this does remove the whole "I paid 39 euros, you owe me updates" entitlement thing from the equation, which I imagine will be nice for him.)
But he and the other guys working on TextMate 2 have had years to do that. Walt Disney, Steve Jobs, and Mark Zuckerberg have all said variations on this same phrase: "we don't make [things] to make money, we make money to make more [things]." Based on nothing but history, and the quality of the software Odgaard has actually shipped in the last four years, it's obvious he's not making things to make money, nor is he using money to make more, better things. It's unclear what his motivations are, but it is clear that his interests are not aligned with his customers'. That is why TextMate 2 took so long to surface, that is why it's crap, and that situation is unlikely to change just because the code is now where people can see it.