Dunno. Ask. Listen. Be humble.
Have a hypothesis and then do your best to falsify that. Give him all of the charity he needs to refute your guess that he's a bigot.
"So you say that there is a convention in Italian literature of depicting other-worldly beings as having freakishly white skin. Would you be ok with the Pinocchio reboot if the same African-descended actress portrayed the fairy, but were instead made up with freakishly white skin?"
If he doesn't refute your generous chances, then guess what? You found a bigot. Congratulations.
If everyone were more parsimonious about it, calling someone a racist or white supremacist or a Nazi would actually have some meaning again. At this point it's just coming to mean "This person disagrees with me and I don't like it".
Remember, these depictions are intended to be immersive. If some element reminds the watcher that they are watching a story, and they find it difficult to suspend their disbelief, they're not going to like it. That could mean an actor with clearly incorrect ancestry for the role.
For example, in the real world, a rural village of people whose ancestors have been in the same region for hundreds or thousands of years are going to look a lot alike. This is why Finns do not look like Khoisan. Everyone knows this. No one has a problem with this.
If your fantasy setting has human beings (or humanoid beings) living for generations together in a small rural village, and you just throw a bunch of different real-world ancestries in there, a Khoisan burgher and a Finnish tavern keeper, that's going to need some kind of explanation. Highlighting that as a problem isn't automagically racist. Maybe it's "magic world" and people there just have that kind of reproductive variability. Cool. Whatever it is, it needs a reason. But without that, it comes off as immersion-disrupting tokenism.
So, no, I don't think "focusing on race" is an automatic signifier of racism.