I think one of the primary reasons Peterson "fans" or "followers" aggressively defend him is that the overwhelming majority of criticism aimed against him has no substance. There are lots of straw men arguments, misrepresentations, and 30 second snippets taken from 2 1/2 hour lectures.
The article in the OP is a perfect example, some minor decent points that have value and truth surrounded in a sea of utter shit.
I'm not going to quote anyone here specifically, but I'll address a few ideas I've seen come up and let the readers think on these points for themselves.
1. The idea that Peterson suggests inaction as the best possible recourse against social injustice / inequity.
This theme comes up a lot among his critics and it couldn't be further from the truth. Peterson suggests inaction as a better alternative to the interventionist approach that is being pushed by many groups across the cultural specrrum. The reason why is because the foundation that a lot of these groups are built on is the same foundation that is the root cause for some of the most disastrous social experiments in our history as a species.
If you take the time to delve a little deeper and do research through a lens of inquisition rather than criticism, you'll find he offers many ideas how people can actually solve the problems of inequality and injustice. I won't get into this topic too much because there is a lot of material, but the guidelines are roughly as follows.
Understand not only who, but what you are (biological history, our evolution; cultural and physical, the manner in which our brains function, how deeply ingrained these systems are into our genetic material, etc)
Speak as truthfully as you can. This means speak according to what you know, how confident you are in your knowledge and don't speak in a manner that can potentially bring harm to yourself.
Don't consider yourself a victim. Always ask yourself what you can do to empower yourself, for yourself, by yourself, take responsibility for the choices you have made and attempt to become a better version of yourself.
Behave in a manner that is not only conductive to your well being, but has the least possible negative outcome for people in your community as well.
2. Why is it okay to be vehemently opposed to Marxism and not Capitalism?
First, this is a strawman argument. Peterson is vehemently opposed to any ideologies thay do not offer a functioning system thay can be implemented as a replacement to the current state of affairs. The reasoning here is rather simple, even tyranny is favourable to the chaos that precedes and proceeds it. This idea isnt really disputable, and if you choose to dispute it you should brush up om your ancient and modern history and then return to the discussion.
I don't think there is a necessity to continue further, but I will anyway.
Life is unfair, society is unfair, the world is unfair. That is the nature of the world, the Universe does not care about equity, otherwise there would be no difference between stars and planets.
No living creature in existence has an equitable societal structure. It doesn't exist. There is always some manner of hierarchy, and there always has been and there always will be. The idea of trying to force an equitable outcome through human intervention goes against the very fabric of matter, literally. In short, this is why a capital based system that acknowledges these structures is the one that has been most functional.
The idea that Peterson is proposing is that if people behave in the manner proposed in the first response, they will make their lives better, and if all people behave in this manner it will make society better. This is the only feasible way to create a system that has less injustice and less inequality. There will always be inequality and injustice, Peterson proposes that ad a species, it is our responsibility to function in a manner that both acknowledges this, while trying to reduce it as much as possible.
I think one of the major problems with Peterson critics / fanboys is that they aren't willing to listen with an open mind. They listen to his words with their own ideas in their head, and as such they use him as a figurehead for their own ideas (wether it be as poster boy for right wing extremism or as a target against the white male patriarchy)
His message, when you clean it up is really simple:
Do your best to understand and be aware of your biology. Speak truthfully. Behave in a manner that lessens the suffering of yourself and others as much as you can.
That's why his critics are constantly greeted with "You don't understand", for reasonable people his message is a positive one, it makes sense, and if everyone lived by it the world would be a significantly better place.