Anyway, it's not nearly as silly as some hairy Canadian with hard bones and some knives beating a cosmic menace like Lobo. You might as well have Wolverine defeat Thor, or Gladiator (and yet, somehow, I'm actually pretty sure that happened too).
Well, given that Lobo only exists to serve as a grotesquely exaggerated parody of Wolverine and similar characters, I can't blame them for letting Logan get some payback. I mean, Lobo is a joke rather than a realistic character, or at least that was the original intent, so I'd expect Rule of Funny to outweigh realistic considerations of relative power levels.