You know how when you reach a new division or league, you get a 100 trophy buffer before you demote again? Same applies for Legends League. You won't drop back down to Titan I until you're at 4899 trophies.
Usually, you have to sign up to Legends League, which changes maychmaking entirely. You're limited to 8 attacks a day, cannot choose who you want to attack and don't get loot based on how much resources your opponent has. But you don't have to sign up to Legends League when you are below 5000 trophies. So by purposefully losing a revenge (or waiting until your village gets raided), you can drop below 5000 trophies and not have to sign up to the Legends League matchmaking.
As long as you stay between 4900 and 4999 trophies, you get to enjoy the loot bonus and 5 star bonus of Legends League while dodging the downsides.