It might be -total speculation- that he got defensive, denied it and since then is keeping up face rather than outing himself as a fool.
It's not the first time it happens (audience identify influence, creator denies vehemently) and I suspect my idea is plausible because some critics and fans are prone to very excessive opinions : they will often overrate the weight of a specific influence, sometimes miscontrue completely them because they're not that well-read (I had one guy telling me the robot designs in Pacific Rim were obviously Evangelion-like. I feel you can only believe that if you're totally oblivious to the breadth of various mecha representation in popular culture, especially japanese. Similar case as Del Toro says he didn't watch Eva before making it.) and on top of that mix and confuse "influence", "homage" with "lack of originality" if not "plagiarism". I think a lot of artists are short-fused when it comes to being lectured to what they really meant by people talking out of their ass, and wouldn't be surprised they'd deny in a kneejerk reaction.
It also happens that different artists may form some similar works from similar influences without being aware of each other too.