If a commenter is notorious enough to have a dedicated thread on here about his disruptive conduct, it seems that a blogger may have good reason to ban them.
Here the blogger gave detailed reason for doing so, and it was not simply about posting about a drop in traffic
I want to see how the comments section is without his incessant [insert whatever you call what he does]. I've informed him of this, but despite that, he has left over a dozen comments since (which just go into the trash folder), now even with different usernames...
There are published commenting guidelines, which he repeatedly violated. The goal is to create a comments section that is useful and constructive. While Tim is knowledgable about some things, the way he expressed himself just created an unnecessary number of distractions.
This explanation is consistent with the posts in this thread.