@Mad Black
It was a story in the Legend universe, so there’s nothing stopping it from being canon in that universe.
No it wasn’t even part of the now known Legends continuity, it was branded under the Infinity label*, like most of the Star Wars Tales Comics, they are official what-ifs, like the Tag and Bink comics and other stuff.
Back then continuity was kinda fluid and there was canon pyramid. L>T>C>S>N.
There was L, for Lucas continuity, meaning the 6 Star Wars Episodes, T for Television, like The Clone Wars, C for the old EU including books, novels, comics, toys, S for the secondary canon, like the old Marvel Star Wars comics from the seventies and early eighties, and N for officially published Non-Canon material, like the infinity comics.