And yet again, you still miss the point. The article states that the scope of HTML5 is so huge, that it will be difficult for browser developers to fully secure their browser against exploits. The scope of HTML5 makes securing the browsers more difficult, and as a counter point, they compare it against HTML4, which was far simpler, but exploits are still being found to this day.
This in no way suggests that HTML5 sucks or is evil, it is just something that people need to consider.
Unless in your original point, by developer you meant Firefox, Chrome, Opera or IE dev teams and by application you meant the aforementioned browsers, then your point was, at best, vague.