Um...no, it doesn't.
The article clearly states "...attackers looking to exploit a bug in the TWiki collaboration software..."
So the hack was on the Twiki software...not Firefox.
Clearly, the "more eyes creates better security" theory is blown to shreds for the vast number of open source projects.
Please. Much bigger holes were blown in the "closed source is more secure" argument with the sheer volume of viruses, trojans and worms spewed by Micro$lop's malware.
You guys have to go out of your way to find isolated instances of security breaches. Me, I get hundreds of copies of Microsoft's incompetence in the form of worm-based attacks in my web logs and e-mail viruses in my inbox on a weekly basis.