The SOP as per the FCOM for Autoland is that at touchdown :
Roll out mode : check engaged / announce
Both thrust lever : Rev max or Rev idle .
Also, SOP as per OM-A for low visibility procedures states that if performing a CAT 3 B approach, "ROLL OUT" guidance is required
So if after touch down if the ROLL out mode is not engaged, and you see the yaw bar, there is not reason why you shouldn't continue. Note that 3B condition you will have at least 50m of RVR.
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