The nonstandard definitions and notation, the lack of proper typesetting, random clip-arty images, the precociousness of "Grand Unified" whatever, and the general pretense that this isn't covered in most intro algebra graduate courses, all of that doesn't help his case. :(
I guess if it were purporting to be a text book rather than a blog post, these would be issues. As it stands, he's just someone on the internet sharing his thoughts.
I'm not sure what you mean by 'precociousness' there, since I imagine you're not attempting to compliment the author—but he's hardly alone in considering Geometric Algebra to be a kind of foundation/'unified theory' for large swaths of mathematics.
The other critiques seem mostly along the lines of, "he doesn't dress like us", which, while maybe a little off-putting to the in-crowd, shouldn't earn him an automatic dismissal or derogation.
Of course people can write and wear whatever they like. I am simply explaining why it smells like crackpottery, since it seems you thought it was only due to that one sentence.
And, for the record, anything aspiring to be a grand unified theory of mathematics has to go far beyond algebra.
That's fair. In my initial comment I was using the quote as an exemplar of an idea running throughout the article--but my reply was directed more to the three comments implying the author is a crank than to yours in particular. As for the unified theory bit, I agree (you can see this in my previous comment) that Geometric Algebra wouldn't cover all of mathematics.
