A rhetorical question: if you see someone performing and they behave badly, treat others horribly or make people uncomfortable, should you say something? I’ve taken both approaches and I really don’t know.
On one hand, no one wants unsolicited advice. On the other, I don’t believe that people want to look like insensitive jerks.
I suppose one could ask them privately if they want to hear some thoughts you have about their performance. If they say yes, then one has an open invitation. If they don’t, then move on.
The only caveat is that you would need to be kind in your delivery.
