There are talks about FB most notably at the recent DC. They mentioned that there was no clear cut rules, but bible principle to follow when using them. Many elders I know use them.
It's terrible how Satan uses people against God's Kingdom
What I think is terrible is how others(simple disbelievers), and not just in this case can be automatically classified as "instruments of Satan" and "tools". This was discussed brielfy in CoC(still reading).