uhh, that's a weird and likely misleading statement. the MIT/X11 license is as much of a free software license as it is an open-source one. likewise, GPL and AGPL both qualify as both. the definitions of FS and OSS are essentially equivalent, and OSS's was meant to be equivalent to FS's. goals of supporters of each are different, and that leads to different preferences, so your diagnosis is not unfounded. https://www.fsfla.org/blogs/lxo/pub/against-software-tyranny has more details