These type of organisms -- those that seemingly require a rather narrow window of living conditions -- make me wonder how they have survived through ice ages and such.
I assume this has been something extensively studied and is well-understood in biology or climate science.
They survived the same way that any other species survives: by finding an ecological niche in which they are better adapted than their competitors. That niche doesn't have to be very big, it just has to be big enough. During the ice age, the niche for this flower was in the tropics somewhere.
I had the opportunity to see one of these flowers bloom in 2018. It's quite phenomenal and I hope they can stay away from extinction through the next millenia.
I was lucky enough to attend a university that had one in their botanical gardens. I was also lucky that it bloomed when I was there.
Saw one of these at the Chicago Botanical Gardens a few years ago. The corpse smell is not an understatement.