My understanding is that the answers you have so far are correct however this does seem illogical. If you can have a temporary airmans certificate issued on the basis of your CAA / JAA licence then providing your CAA / JAA licence is current you can get an FAA cert issued without any flying or verbal theory test. Why then should you have to get a BFR?
Person A turns up with CAA licence and gets a temp cert and is able to fly immediately.
Person B turns up with CAA licence and has to do a BFR. All because person B has botered to get an FAA licence in the past and has probably therefore donw more flying in the U.S than person A.
See the logic?