I'm the original author, and I agree with your point. I do think the things you produce are part of your identity. It's when a person mentally replaces "part of" with "is" that it becomes dangerous.
We can be so much more than the artifacts we create.
One thing you didn't mention in your article, but which I think is a relevant and interesting observation to make, is that 'your code =/= your identity' works both ways.
It's not just that you should not project messy code onto someone's personality/identity, but you also cannot reliably do the inverse. I know people who are meticulously organized in everything they do in real life, who hate to be around a mess, who always want schedules, predictability and stability in their daily life, who optimize their daily routines to perfection. Yet they write lousy code, take shortcuts, do not think the problems they solve through enough, etc. Likewise, I know people who are chaotic in every way, who don't adhere to many of the things almost everyone else considers to be the norm, who have little to no self-discipline for mundane tasks, who are non-conformist by choice, and who are often perfectly aware of these shortcomings. Incidentally, I count myself into this group. Despite all this, I consider the code I write to be very thorough, organized, maintainable, proven to be very resilient to bugs, efficient, etc. The process that gets me there may not be the prettiest, thought-out, elegant process you could imagine, my workspace may be cluttered with 10 terminals, my temp dirs maybe full of old cruft, and so on, but still, I consider the products of my work to have all the qualities I seem to lack in real life.
So apparently, personality really doesn't say much (if anything) about the quality of the software you write. It's a profession that is so far from our daily lives that you cannot project one onto the other or vice versa, exactly like you already wrote.
Likewise, I know people who are chaotic in every way, who don't adhere to many of the things almost everyone else considers to be the norm, who have little to no self-discipline for mundane tasks, who are non-conformist by choice, and who are often perfectly aware of these shortcomings.
You'd consider those to be shortcomings? I'd consider them to be strengths. Granted, you can take those strengths too far such that they become weaknesses. But as long as you're careful not to turn them into a Golden Hammer, I wouldn't count those as weaknesses.
In some ways I can imagine they could be strengths, or at least beneficial in some situations. For example being chaotic and non-conforming sometimes you learn something you would otherwise miss out on. Most of the other things I mentioned only work against me, such as lack of discipline, not finishing stuff I started, or lack of focus and not being systematic enough and getting hugely frustrated about forgetting where I left something.
I guess like always, truth is somewhere in the middle.
Right, when I got my current gig, I took a HUGE ego hit because I went from just committing stuff to getting absolutely everything code reviewed, and that means bugs in my code were pointed out before I'd had a month to think everything I'd done earlier was crap :) You definitely need to be more to yourself to weather harsh lessons.
We can be so much more than the artifacts we create.