Ooh I haven't been able to look at the auction site yet, so that's pretty cool! I think restoration could be possible if you have the right tools and take your time with it. Your success might also hinge on whether the Boo Blasters figures were attached to the SDatHC figures with screws, nails, or some kind of adhesive. Screws or nails should be easy to remove (and you'd also be able to keep both figures), but if it's adhesive then good luck. These were probably never expected to be separated so the adhesive could've been dabbed on or spread all over. If you're lucky it'd come off in chunks, but otherwise there will be some sanding involved.
I suspect that they used screws since the gap looks so small and adhesive would have a harder time sticking to a smooth surface. Maybe I can look closer once I open up the website for myself.
If anyone does manage to snag one and attempts to begin a separation/restoration process, be sure to post it! I'd love to see how they were attached and how it all turns out.