My comment was based on my experience with this species. They're a lot tougher than most folks think. I've found that most 'references' exaggerate the cold sensitivity of plants. 59? For a Ficus?
My low 30's number may be a little risky, but 59 is just crazy.
I shuffle lots of trees in & out in February. I left a bunch of microcarpa cuttings out all winter, and all are doing fine now. Not even a brown leaf on them. We had a few nights in the low 30's, and one a tick or two below freezing.
Lumping tons of species together with blanket statements like 'all tropicals need protection when temps hit 50' seems like a poor way to provide specific information. Even if you wanted to use that as your guide, Ficus is generally considered to be sub-tropical. Different than a true tropical, like Buttonwood for example.