So 1. It's a relatively small risk but still a problem and 2. He didn't even mention this risk. It doesn't make this variation outright bad(although this IS a problem, or at least a big disadvantage, if you want to get into the specifics of the terminology), but it makes the blog bad. The good thing is that the fix is easy, just mention this.
I actually chose to ignore this bf5 possibility since its a small risk (as you say) and because coming from the perspective of having played the four pawn attack beforehand it's not a downside but just a missed upside.
In addition, the line after bf5 Nf3 e6 Bd3 Bg4 c4 achieves basically the same thing (like you also mentioned!), effectively reducing the chance to play main line against an unknowing opponent by 90% and making it possible to surprise a prepared opponent one more time.
And by the way I don't expect my opponents to have read my blog.
BUT when I find the time, I will add this line into the blog so hopefully you are happy
BTW! Maybe you could write a good blog to show how it's done! That way I could learn from a professional
Unfortunately, it's not more a secret.