I disagree with the way this was said but I completely agree with the message. Its not right to shame anyone's body. All that matters is that a person is happy and healthy. You can't tell whether someone else is healthy just by looking at them. Some people are meant to be skinny and some are meant to be larger. Leave that between them and their doctor.
I also have a huge problem with double standards. You have no business complaining about any prejudice, body-shaming, and whatever else that you experience if you turn around and do it to someone else.