Equating "Here's the full source code and you can do more or less what you want with it, except this one specific thing because it would really harm the future

Equating "Here's the full source code and you can do more or less what you want with it, except this one specific thing because it would really harm the future development of this software" with "proprietary" (that is, "no access to the source code at all") is just silly and ridiculous.