Premise 3 is false.

If person can choose A he can equally choose B or C or D etc. However the person only does one. The rest are all fantasy.

Determinism demands an outcome, and humans are the function. A becomes B with[out] you.

Sabine Hossenfelder's video on free will discusses this much more succinctly, with an ontological framework that has some basis in the metaphysical.

Huemer fails to address human perception's role in deciding the epistemology of this argument.

I love this comment!

Human perception is the limiting factor for defining truth.

No reason we can't explore the 'yet-to-be-known', assume it's identity, or make explorations on that assumption.

In the end, the discussion about truth will still be limited by the parties having the discussion, and what they agree upon as 'reality' or 'truth'.

For me, morality exists in respect to the harm principle. The responsibility of the harm comes down to whether the human is aware/recognizes the harm as such. Is it always bad to cause harm? Religion requires there be a God that approves and disapproves of types of harm, and that it be obeyed. Why not discuss what harm individuals are willing to accept instead? This might be objective, or it may just be a construct of human society, of human perception. Good is relative to the human after all.