I agree with you. People are imparting their own interpretation of the word. When I skimmed the web site, I didn't notice anything relating to the whole "brogrammer" thing.

Just because it starts with the same three letters doesn't mean anything. As already stated in many other comments, "bro" is also, and more commonly, used as a substitute for other colloquial words such as "man", "dude", "guys", and is frequently gender neutral.

These niggling complaints of offense where none was intended is indeed getting old. The author's intent is what actually matters, not how someone else interprets it. A reader gets to choose whether to be offended by a word or not, he doesn't get to choose the author's intent.