You're kind of stacking the deck here. It's true that a programmer who knows for certain that she's never going to make her code proprietary would be behaving i

You're kind of stacking the deck here. It's true that a programmer who knows for certain that she's never going to make her code proprietary would be behaving irrationally to insist on keeping an option she'll never use. But that's a rare case. What about the more numerous programmers who don't know for certain? If they choose to keep the proprietary option open by eschewing GPL-licensed code, that could be perfectly rational, depending on the value to them of the GPL-licensed code they're declining to use. And what about the programmers, like Daniel Jalkut, who work on proprietary commercial projects? Of course he'd prefer for other projects to use liberal licenses that would allow him to make use of them. That's the opposite of irrational; it's just straightforward incentives.