My headcannon for Loki's plan for the end of the bet was that he was planning to try and get the world (and all the souls Hel would stand to rake in suddenly) devoured by the snarl to prevent Hel from gaining too much power without undercutting whatever his motive for the bet was, which I believe to be teaching his daughter a lesson about a balanced diet.

Then the dark one appeared and he saw a chance to end the cycle, and had no qualms ditching the lesson and just letting Hel rot for all eternity because he's Loki.

Voting not to destroy the world, as a happy coincidence, serves both of these goals.