Athena's "white" was not in reference to Trump supporters, but to the liberals that oppose him. She singled out "whites" among liberals who irrationally believe that Trump's current supporters will magically move away from him once Hillary exposes his idiocy.
Not exactly. This is one example of a general belief that explanation and exposure to facts leads to people, in this particular case white people, to change their minds on issues.
She'd be all over anyone making a parallel comment about blacks, when its obvious that race is at most a non-causal correlate for the behavior.
Feel free to make a parallel comment and find out.
As for the choice of saying White People ...
White people are the dominant race and the beneficiaries of white supremacy in the US. It is the dominance that leads to certain behaviors that are only open to white people. No, it is not the deficiency of pigmentation that causes anything really, outside of sunburn.
The OP is correct about the naivete of many liberals, but it is tied to a variant of liberal ideology itself, not race. Among older adults, (e.g., 40 and up), this tends to mean mostly whites because few non-whites of prior generations are actually liberal, rather they are more akin to socialists and/or religious conservatives mixed with self-interest in strongly supporting government coerced racial equality in outcomes. IOW, they are "left" but not very liberal in the classical sense of valuing personal liberty rather than merely equality of outcomes.
