Loftus says on p. 59 that he has "an antisuperstitious bias". What he really means is that he has an antisupernatural bias. Having an antisupernatural bias is basically a dogma. So, when he says he has "an antidogma", he is not being honest. Since no person can guarantee there is nothing supernatural, remaining closed to the supernatural is tantamount to intellectual surrender.
As stated previously, there is no “belief vacuum” from which an impartial investigation of beliefs can be conducted despite what Loftus says. A critique of a belief is born out of another belief. Otherwise, there would be no frame of reference for the critique to be created from, no basis for comparison. A person wouldn’t even know how to evaluate a belief system without already subscribing to another one.