You are mad at the person who said that, upon hearing them say it, for being wrong and then made a post about it which is the appropriate response.

Seems it’s possible to me. You’ve just done it, OP.

It’s a quote attributed to Aristotle.

In that light, such anger would be virtuous (being neither too extreme nor timid, too late nor early, based on the proper reason, and with an appropriate response).

It’s too bad none of the “decline of Western Civilization” people care to heed this quote. They seem to have abandoned virtue altogether, preferring vice and viciousness instead.

I think it’s very possible.

With the right causation or correlation, the correct person is identified.

Whether right reason refers to being mad at the person for the related reason or the reason itself being valid and rightful, both are possible.

Right time is related to the cause of anger as well as when the anger takes place. Both is possible to be at the right time.

You can even be angry without any visible indication. There’s also cases where an aggressive response is the right response. Proper response is possible too.

It’s a vague statement. Enormous wiggle room. I think there’s a valuable idea somewhere in there about reflecting on the root of a problem, but the conclusion is overly fatalist. It’s OK to hold someone accountable even though they are part of something bigger.

I’ve been thinking on the original of this sentence (Aristotle’s Nichomachean Ethics, book IX) for a bit. I’ll copy the relevant excerpt:

That moral virtue is a mean, then, and in what sense it is so, and that it is a mean between two vices, the one involving excess, the other deficiency, and that it is such because its character is to aim at what is intermediate in passions and in actions, has been sufficiently stated. Hence also it is no easy task to be good. For in everything it is no easy task to find the middle, e.g. to find the middle of a circle is not for every one but for him who knows; so, too, any one can get angry- that is easy- or give or spend money; but to do this to the right person, to the right extent, at the right time, with the right motive, and in the right way, that is not for every one, nor is it easy; wherefore goodness is both rare and laudable and noble.

I might not agree with his “middle ground” reasoning (I think that it’s simplistic) but I agree with his conclusion - to express anger can be good as long as you do it without misdirecting it, overdoing it, doing it when it doesn’t matter, doing it for spurious reasons, or doing it non-constructively.