That would mean effectively surrendering the ability to ever make money back for time I've put into drawing the font, so I'm not entirely sure why I would want to do so?
Edit: non-profit license vaguely maps to CC-BY-NC though.
As per licence text, CC-BY-SA only requires that you distribute your contributions to the material (so, in this case, font edits) under the same licence, not that you distribute your projects under that license. So that's LGPL rather than GPL.