Perfect. Thanks.
It looks great here, but unless you store it on a shelf and never touch it this SNES is going to look like a Max Headroom prop in a year. No primer means it will flake like a mofo, and semi flat means it will probably never cure correctly. From the pictures it looks even less flat than semi-flat, meaning that it may have had multiple coats applied when still wet meaning that it may even smudge to the touch months from now. That part is just a guess though since its hard to tell from the pic and flash tends to add shine to things that aren't there in real life.
To do this right you'll want to prime it (preferably with something hardcore like Kilz since a SNES is all slick and shiny and textured) and then spray with an acrylic base. Clear coat (matte, gloss, or whatever, just use acrylic clear coat if you are using acrylic paint) is optional. Then that shit would never come off. Do this all of course after cleaning the system extremely well. I'm sure there is some way to chemically treat it first, maybe just soak it in whatever the nastiest chemical is that won't melt the plastic. Non-chlorinated brake parts cleaner? Kerosene?
That thing looks great though, and infinitely better that that putrid yellow that so many SNES systems are now.