Just my 2 cents:

A philosophy differs from an ideology. Long-termism is a philosophy, meaning an abstract framework that is used an intellectual aid. An ideology, on the otherhand, is an all-encompassing world view, that inserts itself at the top of one's value hierarchy, and allows one to do as you describe: define any wrong as a necessary evil to fulfil the greater good.

The reason long-termism is merely a philosophy, and will remain so, is that it doesn't provide a narrative that lends itself to ideological zealotry. Ideological narratives are simplistic models of the world that can be easily digested, and provide a ready litmus test to categorize any person into one of three groups: victims, villains, or saviors.