Earlier quoted context omitted.
The idea of free software is that user can (and have the right to) modify it in any way one wants. If I found a bug in free software, I can fix it by myself or wait for someone else to fix it, or pay someone to make a fix. That's the way it works. (edit: typo)
But what's the difference between open source, free, and "source available" for inspection?
Free software: free for modification, expansion or forking. Possibly free for profit (BSD license)
Source Available: Source is available but under restrictions. Locked room source viewing under NDA to confirm there aren't vulnerabilities for example.