I also don't understand exactly how Facebook features work,not being on it myself
However, I did quote this from one of the BBC articles:
To expand that point slightly, if the account is set to private, then presumably only friends and family can view it. Thus, anyone pretending on here or elsewhere to be authoritative about it, without talking to those friends and family, has either been clairvoyant enough to befriend this person before he died, or may be fabricating or wildly assuming the pretended direct knowledge about it, such as timestamp when it was recorded, and/or time when it was posted to the account.