What would be the plan to control costs? Fe2O3 nano particles aren't cheap, as you can see. At $3M per tonne and the need for, say, 10 gigatonnes to start off... That would put the cost of this plan at $30 quadrillion. I'm sure that, at that scale, the price would come down, but that's a pretty high starting point. Toss in the fact that these nanoparticles would naturally settle out over time and the costs would increase further.

No one said terraforming was going to be cheap, but at that price, there has to be a less expensive option.