As long as you recognize that corrosion converts metal to powder so the wheel will be slightly less strong in that area. The primer and protective silver paint has also failed or there wouldn't be corrosion. The weakest spot in our wheels is the inner bead where the tire seats, and it's worst on the inner bead of the more heavily loaded rear wheels. Water inside a rim usually comes from a poorly maintained air compressor that concentrates water as it compresses moist air.
Sure- you can thoroughly wire-brush the white mag-oxide away, spot-prime with zinc chromate (if you can find it) and spot-paint with Argent Silver metallic paint, which should match Campagnolo's stock paint. Be lavish with the primer & paint- the more layers of protection, the better. Just keep an eye on the area in the future and don't stress the rim too much; high speeds on potholed roads, or autocross competition might best be avoided if the affected area is large.