I can only imagine accurate KOs devaluing legit toys when they are very common and competitively priced. I don't think the KO Headmaster heads apply as they are not common nor competitively priced.

The reason why reissues devalue the vintage article is because they are competitively priced and easily available but as the reissue 'ages' and becomes less common, it eventually balances out with the legit article as the reissue begins to increase in price.