I admittedly don't know much about Omni-Man sadly. I have meant to check out that book for a long time but never have. From what I gleam though, he is practically a Superman level character which makes this battle sort of one sided. As strong as Juggernaut can be, if Omni-Man is as strong as he seems, he'd just grab Juggernaut and toss him into the sun before he even knew what hit him. No time to get moving.