Gangplank in support?

It's a vestigial label. Ages ago, before his kit was gutted and re-gutted and then reworked, he had elements that could allow him to support (his heal could heal himself or allies or both, I can't recall).

He was once a support because of his on hit slow passive and his Raise Morale ability in which he'd shoot his pistol into the air granting a buff to himself and nearby allies. Prior to his rework, I played him somewhat effectively as a support.