It's something of a moot point, as I haven't hacked Tahoe-LAFS. But yes, other than to the FSF, and in a pinch to some other organization with similar structure (non-profit), credibility, and guarantees (that my code would not be used in proprietary software), I would not do assignment under any conditions. It's too unequal of a transaction.
Even if I wanted to permit my code to be used in proprietary software, I would not assign: an MIT or similar license should be sufficient.
I would enjoy listening in to a conversation between you and Meeks, some time ;-) He's really on-message these days about the evils of copyright assignment, and I basically agree with him.