I read the text as the author is not against weapons as such, he is advocating for making people to attend mandatory courses before they can buy a weapon (the same as people take driving lessons before driving a car).
And he is an interested party — he already runs such courses and he hopes that if the government makes them compulsory, he will get more customers. So in some way his text is a lobbing for a government policy that will benefit him personally.
I don’t live in the States. I had some military training when I was younger and the first thing they teach you is to how to handle a weapon in a safe manner, even if you think it is not loaded. As a result I can’t watch someone mishandling a gun. I remember on a Safari in Kenya I was more frightened of a guy with a rifle who was with us in case a lion or crocodile decide to attack, then of actual lions or crocodile — the guy was obviously not trained properly and was carrying his rifle in a very casual manner.