Mathieu, Technical issues: can't build from source. Would be fine for contrib, though. Legal issues: couldn't get an answer from Adobe, who then abandoned the project. Would be fine for non-free, though.
But nobody wanted to entertain the idea of putting this package anywhere but main. Personally, I don't see how no package at all is better than a build-dep in contrib or non-free. I gave up trying to convince anybody and finally left the mailing list. I don't even use Flex these days, so I see no point in fighting anybody over it. You can search my name in the debian-mentors mailing list archives if you want to see some of the discussions that happened around this. --Joey
