I think in the beginning there's too much that can overwhelm analysis. My suggestion, don't worry about when things don't go as planned. It happens all the time.
As Uke give your best attack, with intention, with determination. If things don't work out for Nage, and you "know" what's happening you could speak up if that's ok in your class (local customs vary). But beware, since a frustrated Nage can bite back out of irritation.
Personally I wouldn't be offended either by your comment nor by the response (which is BS in my mind). Later Nage may realize that you were right.
Sometimes the point just doesn't make it across. Don't beat yourself up over it.