You are conflating free-as-in-freedom and free-as-in-beer.
Software can be free (as in freedom) and open source while still not being free as in beer (ie, charging money).
davexunit is commenting on the fact that the Atom editor is proprietary (non-free) software, which has nothing to do with whether or not they are charging for its use.
So if its too ethical to pay for quality software, just think about your own job, you get paid, right?
Sublime is not free, still people create packages for it, for free.
Do you mean that if the code is open to everyone, the software should not cost?
Kind of weird, using open source software to create software to make money, but not being able to sell software for money if its opensource.