Can your contractor replace the column with a red oak one?

I'd like to suggest something else. One way to get a more serene effect when deciding what finishes should go where is to match things according to the plane they occupy.
So that would mean that the stair treads match the floor, since they are low and horizontal (you have that...). The stair risers match the trim, since they are vertical (you have that, too). Using this scheme, the post would match the balusters. If you are using wrought iron, can you consider using a wrought iron porch column, like the ones you see in New Orleans? I think that might give you a nice decorative touch, if it isn't too pricey.
Depending on where you live, an architectural salvage yard is sometimes a good source for such things.
Otherwise, a nice oak 6x6 with flat-paneled sides and crown and shoe molding would look very nice. Your finish carpenter could build that for you by adding 1x2s around the edges of the stock 6x6.
Now here's a third idea.
A white post doesn't make sense with black balusters and oak handrails, but it might be nice to avoid a tall dark thing standing in your view of the downstairs...so you could use a slender oak newell post that is tall enough for the handrail to die into, and then use a 4x4 painted to match your walls to extend to the ceiling and provide the proper support.

I seem to have really gotten into this this morning! Sorry if it's too many things!

Another option is to wrap it with drywall and paint to match your walls.

I totally agree with "lyfia". We have a column exactly like yours and the builders have covered it up with the dry wall. it looks very decent that way.