I don't think Facebook let's you know why they banned someone specifically, or do they? It could be; you assume it would be for this comment, but it's not outside the realm of possibilities that something else triggered it, right?
I did not see the actual screen where it shows you what you were banned for, I just helped my mom submit her driver's license photos and so forth, and it wasn't until a couple days later that she was presented with a screen that, by her description, was essentially identical to the twitter screen that shows you your offending tweet, and asks you to remove it in order to continue using the service.
