It feels like bait and switch.
I also showed him the RepRap, and he was immediately turned off of the idea... he just wants something easy, polished, and more consumer grade, not "hacker" grade.
I am a huge fan of Open Source, and have no problems with using Open Source in a commercial manner (I actually have a commercial software product that uses some Open Source components), as long as the licenses are being adhered to.
Bri Pettis strikes me as being a solid guy, and I believe his intentions are honorable, and he will do as he says, and ensure that everything will follow all the license requirements.
It's understandable that he has to be a bit protective of some aspects of his products, as I think the big players (Epson, HP, etc) could become a real threat as soon as they twig to the fact that there's a reasonable market there.
I can't blame him for trying not give the proprietary aspects of what he's doing to his competitors, especially when they're 800 lbs gorillas.
I think that balancing the need for protecting your investment and meeting the requirements of various Open Source licenses is a bit tougher than some realize. It's not just a case of "release everything to the masses", it can be quite complicated.
For now, I'm willing to give him (and MakerBot) the benefit of the doubt, and trust that they'll Do No Evil.
The primary asset Makerbot has is the community. Its fine to polish the product to make it more useful to those less skilled, but lock the community out of the product by closing up the software and its over. That is exactly the advantage someone like HP needs. Theirs is going to be just as good or better eventually with or without Makerbot's suuuper secrets. In the end, the only differentiator will be community.
To start with, it might be a few of the hard-core early adopter, hacker types that will help develop the product, but it will eventually move away from that and become more a straight consumer community. (That's my guess, any way).
For instance, my dad will probably buy one and use it a fair bit for various projects, but he's not at all someone who'd give anything back to the "community", other than his cash.
And while it is the initial "hacker" community that will give it some momentum and critical mass, it's the "cash paying user" community that will really drive development forward.
$0.02
MakerBot was a fork of RepRap. RepRap is still open source.