Yeah, precisely. Paints come packed with pretty harmful chemicals that are the bonding agents and since you are going to be painting the skimmer, you still will leach chemicals in your tank regardless of how long its been out in the sun to cure. Salt water has a knack to break down everything even the strongest of paints such as epoxies that are used on shipping vessels.
I would advise not to paint it. However, if you still want to paint it and going more for aesthetics, I would still suggest to go the zero VOC route. This is piece of mind when you introduce the painted body skimmer into your tank, that there are no harmful chemicals leaching into your system. Lowes carries the Valspar brand that I used w/zero VOC's in it in jet black. It wasn't the spray in the can though. I am quite sure that if you do some research on the net for zero VOC spray paints, I am sure you will run into something.