Earlier quoted context omitted.
I'd argue that any organism is inherently open source, just not necessarily free and open source.
By that logic you could argue that software is inherently open source.
Assume your code will be disassembled at some point by a bad actor. Don't assume that any code distributed to a client is safe or trustworthy, and expect that any data, methods, or secrets contained in that code are now public knowledge. To secure your environment systems under any other assumption is a dangerous falsehood.