Well, the point of the feedback is to help the speaker improve their speaking skills, so we're supposed to focus on that and not, for instance, give a well-presented speech bad marks because it supports a political position we oppose. There's also a lot of emphasis on encouragement, saying "Here's a suggestion for how that could have been better" instead of "You did that wrong", and so on.

If I do go ahead with the response, I'm going to try very hard not to make it a direct comment on the other person's speech, just... a speech on a related topic that happens to include some information and viewpoints that I happen to feel the other speech lacked. If you see what I mean.