It probably falls under both actually, depending how you classify "player A is not entitled to have an opinion because player A is not a highly ranked player". It is both an attack on the person's credibility, as well as a refutal of the "Player A is entitled to an opinion" argument, which is not what is being discussed.
When someone says they're "entitled to an opinion" what are they actually saying? If you take it literally it's completely absurd. There's no way to stop someone from having an opinion. You can prevent them from expressing it, sure. But preventing someone from having an opinion? The very notion is just silly. You might as well say you're entitled to think.
But when balancing the game you're not after people's opinions, you're after sound judgements of unit performance. And how do you decide who's judgement to trust?