Well, on the upside the author has at least done enough research to discover that people who ought to know (such as G. K. Pullum) recommend against even trying.
On the downside they're trying anyway, confident that if their rules are just vague enough they're bound to help. I notice that they haven't tried the benchmark Professor Pullum implicitly offers, typing several pages of a major literary work (say, Moby Dick, or Pride and Prejudice) into this software with everything enabled and verifying that it flags none of the excellent prose as incorrect. I think that building a collection of such inputs would have been simultaneously a good practical test of the software and a disheartening lesson on the difficulty of the general problem.
Several of the rules cited in that link seem harmless, but aren't grammar rules at all. Choosing to highlight violations of style such as double spacing may or may not help people, but it has nothing to do with grammar.