Here, your attitude causes two problems.

First, you know and apparently like Kyle Isom, and so I presume you're also ready to tell me that he's an adult and a professional. Professionals do one of three things with criticism: ignore it, rebut it, or learn from it. My assumption has been that Kyle is choosing options (1) and (3) from that list. But here you are, inventing option (4): "get indignant about it". I wonder if you've thought about the extent to which people will attribute that response not to you, but to Isom.

Second, whatever you might think about the tone of my feedback, it's clear that Isom needs additional technical review for his book. Whipping up a totally unproductive us-versus-them narrative about "jerks" versus "open source" does the opposite: it generates drama. Even if you think my review was itself dramatic, piling more drama on doesn't make Isom's work more attractive to experts.

I'm not sure how big of a deal either of these issues are, but they're a bad habit for message board denizens. The exact same thing happened to Willem when he wrote his critique of the Akamai allocator, and Hacker News had a totally unproductive drama storm for a couple hours before Akamai (a) thanked Willem and (b) acknowledged that he was absolutely correct. Read the Akamai comments on the HN thread, and apply them here, substituting "Kyle Isom" for "Akamai", and I think you'll see that they apply.

Finally, I'll admit to being personally irritated by the claim that I operate from "experts only" logic with regards to cryptography. There are at last count something like twelve thousand people who have reached out to us for our free crypto challenges, and thousands of those people have gone on to solve multiple sets of challenges (something like 60 people have finished the first 6). Every damn one of those people is an email exchange that me, Sean, or Marcin had to have directly, on our own time, with no compensation --- the opposite of compensation, in fact, because we donate to charity when people finish them.

There are a lot of people on the Internet to whom you could direct the "experts only elitism" criticism regarding crypto. I am not one of them.

What's more annoying about that bogus critique is how it muddles a real issue. I'd like many more people to understand crypto and, particularly, what goes wrong when it's implemented naively. But I'd like far fewer people to plow ahead and implement their own broken stuff. The track record on amateur cryptography is bad, and what developers don't like to acknowledge is that the badness that work generates is an externality to them. People have in the real world been hurt, physically, because of broken amateur crypto. It is hard for me to take the hurt feelings of developers all that seriously by comparison.