Maybe he could have ended it easily. Maybe he could've ended it with considerable effort. Maybe he couldn't have ended it at all.
The writers had an opportunity to use LT as a factor or a non-factor in the Chaos War, depending on how it was explained.
They could've used him to stop the Chaos King. They could've used him to try and fail which would've established new limits to his power and influence. Or they could've merely shown him on the sidelines watching events play out, waiting for the time is right for him to intervene (should that time even come).
They haven't done any of these things yet and they still could/might, but it seems unlikely that LT will even appear let alone be a deciding factor in this story-arc.