I may not have gotten this across properly, but the same is true of WebKit or rather its KHTML/KJS progenitors (KDE is an open source community and its trademark-holding legal entity is a not-for-profit).
I'm pretty sure that was exactly Gassée's point, though it may not have been clear enough. Linux and Webkit (and Apache, etc, etc) are very successful FOSS projects, but they grew organically out of open source and weren't closed software that was thrown over the wall of a company later in life like WebOS will be.
One could point to projects that were handled somewhat like this and were still successful (like Mozilla), but IMO there's still a valid point that situations like the WebOS release result in stalled projects more often than they result in a successful long term FOSS project.
Unless there is very clear and committed leadership (which would probably have to come out of whatever is left of the existing WebOS team to have any sort of authority), the project will be doomed.
It's difficult to tell which side WebOS falls on, as parts of it were open source all along, and Palm/HP has always embraced the hacker community since the Pre came along (allowing booting from USB, custom kernels, Preware, root access without jumping through hoops, etc). This could be a natural progression, or it could be a last-hurrah. It will be decided in the marketplace, not in the media, and it won't take long to find out. The next 6 months will define WebOS' future, if other companies jump on board or not. A system doesn't often get three chances at success, and WebOS has used up two of them already.