This is not correct and has been discussed many times and clarified by the BA FT rep.
The phone charge should only be waived for something that can normally be booked on BA.com but due to a temporary problem cannot be done.
It has never been possible to book AS awards on BA.com and so the phone charge should be applied. The fact that some agents waive it is outside BA's policy.
Apologies; apparently I had this totally wrong! That said, I have on more than one occasion been quoted prices without booking fees. Is there some exception for Gold card holders?