I'd say that it stretches further than just "having a different opinion" when (i) it's a very relevant factor in the context of what's happening (the appointment), (ii) this "opinion" becomes a replacement for scientific consensus in decision making.

For instance, we wouldn't say that a parent who refuses to vaccinate their child is simply someone with a different opinion. True, they have a different opinion, but that's not what makes the matter dodgy - it's the imposition of that opinion where the stakes are high and we can't afford to have mere opinions.