I interpret him to be saying something fairly non-dualistic - namely, that morality is not an ontologically basic thing separate from physics.

I did not like the particular way he was trying to make morality relate to physics. I thought it asserted a confused relationship between 'is' and 'ought'.

He also may be saying that moral claims reduce to fact claims in some sense, which is almost true (you need to throw some values in as well).

I think that was a point that he was at least trying to make and it is something I agree with.

Are you coming at this from the perspective of a moral nihilist?

No. That's for people who realise that God doesn't tell them what morality is and get all emo about it. I more take a 'subjectively objective' position (probably similar to what you expressed in the previous paragraph).