I would do my best to follow the instructions on the application to the letter (if spelled out). Following a FB post needs to be evaluated for the 'post-er' and date. If it is for a specific airline and it 'goes above and beyond' the minimum outlined in the instructions, I'd say do it.

If, however, it contradicts specific instructions on the application, I'd personally follow the directions on the app. Not only are the applications generic, they also change over time. The FB post may be 'outdated information' and by NOT following the directions on the application (if spelled out) you may be shooting yourself in the foot. Just my opinion regarding following directions and attention-to-detail, both of which most airlines value.