Hmmm.
It comes up as a result when you search United.com, but the link provided re-routes to the generic Travel Options page, which doesn't have any information on the LFG.
https://www.united.com/web/en-us/app...re%20guarantee
I think the guarantee is no longer offered. Considering the crappy new website, I am not surprised. Probably allows for much more dynamic pricing scenarios....