I think what Sleaker was trying to imply with this comment:
> it was open and free, just not fully considered FOSS
is that MAME was open (the source code was published, and updates were continually amended to that publication) and free (the developers of MAME did not charge a fee for using, reading or otherwise obtaining either the source code or compiled binaries). Whether or not there were additional restrictions on how you could use it (freedom of use) is somewhat tangental to their point.
Additionally, as you can observe, both "open" and "free" are lowercase variants of the words, where as you write "Free Software" and "Open Source", which are capitalized pronouns. Open Source and software that is distributed openly as source code are different, but they are cut from the same cloth. Being pedantic doesn't help anyone.
> it was open and free, just not fully considered FOSS
is that MAME was open (the source code was published, and updates were continually amended to that publication) and free (the developers of MAME did not charge a fee for using, reading or otherwise obtaining either the source code or compiled binaries). Whether or not there were additional restrictions on how you could use it (freedom of use) is somewhat tangental to their point.
Additionally, as you can observe, both "open" and "free" are lowercase variants of the words, where as you write "Free Software" and "Open Source", which are capitalized pronouns. Open Source and software that is distributed openly as source code are different, but they are cut from the same cloth. Being pedantic doesn't help anyone.