I still cannot see why "proprietary" should mean "with secret source code": its basic common meaning is "owned by a proprietor" and does not refer to closeness or secrecy.
Your own words condemn you :-)This is an accurate description of linux. Linux is "owned by a proprietor", namely whoever (singular or plural) happens to own the copyright(s).
Cheers, Wol -- Anthony W. Youngman - anthony@thewolery.demon.co.uk