How is that relevant? It's essentially equivalent to an ad hominem. Just because the guy wrote bad code doesn't mean he might not have a good point.

It is not an ad hominem because he was not arguing the point was invalid, rather that the guy is foolish to such a statement while not advocating code structure and style. Notice "...is just as important..."

I agree - that file he linked is very difficult to read and would make it much harder for me to find problems.

I don't understand in what way you think the Simple2ZOOM code is deficient. Is it just because you prefer it to be broken into many small files?