This comment doesn't make any sense to me. Why would the existence of a robot copy imply a lack of pain? How can you argue that whether humans feel pain is an unsolved question? Shall we experiment on you instead?
If somebody links "free will" to "determinism", they're very confused about what free will is.
There are a lot of philosophers doing genuinely useful work, but so much of the field is pre-occupied with trivial (and non-trivial) variations of the "if a tree falls in a forest, does it make a sound?" koan.
1. Non-determinism is equivalent to determinism plus extra, random input.
2. The addition of random noise does not bestow free will upon something that didn't have it without the random noise.
3. 1 and 2 imply no non-determinstic systems can possess free will if deterministic systems cannot possess free will.
4. 3 implies free will is independent of determinism.