Well, I don't agree. If someone wants information, and the best place to find it is on Facebook, which seems to be the case in this particular instance, then suggesting that the poster look for it there seems appropriate. If they're not on Facebook, then they can ask for another place to find the information. In this case, the OP is on Facebook, so the link was helpful to him.
I just don't think that suggesting Facebook as a place to find information assumes that everyone is on there; it's just offering an option for those who are.
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