Sounds like this is a standard "Shimano style" fixing bolt, typical of what would come on a Shimano sealed BB unit, and so it's a standard RH thread and only difference is the tool you use to unscrew it (in a conventional CCW manner): an Allen key instead of a 15 or 14mm wrench.
I was mistaken to think it could have been a self-extracting bolt set-up, and certainly would not be an after-market brand on a Campy crank as that is not possible.
If it was in my shop, I'd use the Monster Truck Tool: an electric impact wrench with an Allen key socket...brace the frame for explosive torque and wear eye protection!
No bolt has ever won in contest against this tool, but sometimes the results are NOT pretty (as in total destruction)!
Still, it's very satisfying when the smoke clears and you're left holding the little b*stard bolt or nut that was making life difficult.
Well worth the $80 or so that Harbor Freight got off me for this thing, and has busted out some really tough BB fixed cups, too!