Software Freedom is the goal.
Copyleft is an effective means towards the goal, but it is not the only means, and it is not exclusive as a solution.
And I'm fairly sure the current parade of developers abandoning their GNU projects - due to being treated shoddily by the FSF - would have things to say about losing control of their projects to hostile forces (e.g. gnutls)
And as a deb dev you also know the debate and position of the many devs who refuse to assign away their rights.