I am worried that someone will actually try this sometime and it will turn out not to work, either because MWI is wrong or because the destruction of the universe was incomplete — for example, collapsing the false vacuum would merely change the state of the things in the universe, not destroy the universe per se.

Fortunately, we don't have any currently promising avenues for nucleating a true vacuum or anything like that, so this algorithm is purely theoretical.

For now.