Open source philosophy:

- If you are given the binaries, you are also given the source.

- You may modify the source to your liking.

- You may distribute the source or a compiled version of it at will.

Note it says nothing about licensing of mods and even the distribution. Each license is actually tackling how modifications and dependencies are treated.

Nothing in the philosophy says you cannot sell it. At all. Nor in any os license.

Remember the first analogy Stalman says: Free software: "Think Free as in Free Speech, not Free as in Free Beer."