Tier 5, 0 LP trolls- How to deal with it.

One of the biggest problems in league of legends, is the trolls of Bronze V, Silver V, Gold V, Platinum V and Diamond V. The rule is, that in order for them to drop a tier, they gotta have really low mmr. So in other words, they can lose 30 games in a row and still not fall. They know that, so they try new champions, play mainly to troll, and don't really care about winning. So, what's the solution?

I believe that Riot should add an "Immunity Option". What will that do? When a player reaches a Tier, he should be given the opportunity to Keep his tier till the end of the season, and get their ranked queue locked (which means they can no longer play ranked till the end of the season) or they could keep playing ranked, but they can drop a tier very easily e.g if their mmr drops 2 divisions (about 8 defeats in a row) .

In that way many people will reconsider trolling a game. However, I believe that Riot wants people to keep playing League at any cost. I am just dropping this idea here. Feel free to argue with me :)