If you're giving something away online for free, then you are giving it away for free. I'll never understand the cognitive dissonance of "conditionally free".
A more important question is where do we draw the line of abuse? If someone links to my website and that's okay with me, but someone else does and I don't like it, do I have the right to conditionally block access to them? And do they have the right to circumvent that to regain access that I freely give to others?