On the one hand, an example of the potential for misuse of any tool by a user (by extension the native security configuration level an app ships with and how well it does in communicating the dangers of changes to the configuration); on the second, the native position of trust or potential harm an app has within the operating system. Those points are of course ranges of gray.
Since those variables weren't placed into perspective in an otherwise balanced article, they will be big points of contention.
A final point, sheer numbers of flaws within a time period isn't a de facto indicator of how secure an app is, especially when comparing both the severity of the flaw and, more importantly, the maturity of the app.
Without any hard data, just a hunch, I think more flaws being uncovered may well be a good thing in Firefox, potentially indicative of a far faster maturation.
Langa Letter: The Pros And Cons Of Firefox