If Gronkowski was inactive for a game, and Hoomanawanui got the starting nod... and you were really desperate at tight end... you would still be scraping the bottom of the barrel to roll with Hoomanawanui. It's always possible he'd grab a lucky TD in that case, and listening to a friend try to pronounce his name might just make it worthwhile. That's about all we're talking about here, though in terms of upside.
His upside and downside are remarkably similar.
There is no league or draft deep enough in which we can recommend drafting Hoomanawanui. He is safely ignorable in literally any format.