Im really confident to tell you that you are wrong here..
Any ways, really no need to call, label anything negative to anybody. Constructive feedback is something everyone would appreciate and is something REALLY fundamental in our society. The way someoone does it is very important. I have read some books on that and if you want i can give you their titles so that you can get better at that. Only in PM so that it isn't spam-advertisment.
All I know is, if you don't want people to call you anything, then don't call that to any one else.
He is a human being, and what if he is reading your words?
Have you thought about the consiquences of your actions towards other people?
Your words are not constructive feedback. It is disrespectful.
With your logic, a bully can use the same philosophy - constructive feedback. Isn't it?
His appearance is given to him by his parents.
How he has aged and what ever else appears on his face is from life.
That is no sin, the only sin is your eyes, and your mouth, or in this case, your fingers, and even your keyboard and internet connection
Any ways, I wanted to translate this, but why should I translate words from a wise person when there is people that doesn't enjoy the way he looks.
To be honest, you don't deserve to get taught by him.
Or would you like to clear your "bully" tag by explain how your constructive feedback can change his appearance and the way he talks?
PS he is a professor for many years. I doubt he needs public speaking lessons. And i'm sure he doesn't give a damn on what his students or audience thinks of his appearance. His value in life is his knowledge and his willingness to share.