Problematic

So, there is this (big) guy at the gym, he is 210cm and 105Kg which makes him looks like a mountain, but he seems to not understand that not everyone is naturally as big as he is.

I wouldn't have asked the question if this was only about me, but yesterday was infernal for everyone.

He uses a lot of space in the gym, he speaks very loud and most of all he looks at everyone and comments absolutely e-v-e-r-y-t-h-i-n-g, which makes people feel really uncomfortable.

Yesterday a girl had to move away from him because she could not stand his behavior anymore (watching & commenting). It was the first time I saw that girl and she was so upset that she told me.

The problem is that you can't say anything to him because he will just deny it and take anything as a personal attack. Every time you're not agreeing with him, his face shows that he is pissed off and he raises his voice.

Concrete situation

I was bench pressing. He just came in front on me just to watch. Once I was done, he said

You should try to bring your elbows as close as possible to you body.

I said that I was doing the thing properly and that I just don't want to try anything else because I just want to enjoy my training safely (mainly if it sounds really bad which in this case, was in fact, bad to do).

I think that he just wanted, in this situation, to make me looks like a weak man in front of two girls that were staying close to us, cause he said it out loud.

Him: Try it and you won't lift as much as you think you can.

Then he just proceeded to bench press on my towel without asking if I want him to show me.

Me: Okay, thank you, but I don't want to change my routine, I am just enjoying my training.

Him: Well, if you always do what you want you won't progress, but whatever, do what you want.

After that he did go talk to another person to tell them how to work out, but for the rest of my training he did not stop checking out how me and my friend are training.

Question

I have been lifting for years and I just want to train peacefully now, so I would like to be able to respond well to people like him. I don't think that they are bad people, they just don't understand how toxic they are sometimes.

My goal is to continue my normal routine without hurting him or making him hate me (intensely staring at me, not talking to me, etc)

How do I approach situations like the one above?