the distinction you're making is not between free software and open source, but between copyleft and non-copyleft. free software tends to prefer copyleft because it aligns better with our values and goals of emancipating users, whereas open source often prefers non-copyleft because it's poorly disguised exploitation of developers, but both sharealike and non-sharealike licensing qualify as free software and as open source. the assumption that free software requires copyleft is a common misconception. please don't spread or reinforce it. defending the freedoms (like copyleft does) is not necessary to respect them, and the criterion is respect, not defense.