They once used electroshock therapy to remove memories. (Mack)

No, they didn't. The indications were severe depression, mania, acute psychotic states. The loss of memory for the periods surrounding the treatment was an unwanted side effect and not the reason for treatment. The same can be said for lobotomy, except that the memory side effects mostly did not only involve memories close in time to the operation.

The drug does not remove memories, it acts upon the emotional impact of these memories, like any other drug-free procedure (hypnosis, reliving,...). If a drug-free procedure works, it is preferable for many good reasons. Only if not (concentration camp survivors, for instance), this drug may be considered an alternative.

But any idea to give this drug as a kind of precaution, after a possibly shocking experience, just in case this experience may lead to a lasting memory with uncontrollable emotions which cannot be controlled in a drug-free way, is silly and dangerous. We might as well tell all women to get their breasts removed (and men the same for the prostate gland) just as a kind of precaution.

Wolfgang