Problem is - that's such an easy thing to say, whether it's true or false. For a device that's owned by millions, it's pretty grandiose of them to think that their internal team is all it takes. There's so much an internal team can do, so having an outside "team" is significantly better - even if it's just for a different view from a different vantage point. So, good on apple for doing this, but I'm questioning their past decisions. In particular their poor use of "they ran out of things to find" is worth discussing. The way this article is worded, their stance sounds incredibly naive, where a, "We don't have the same breadth as the infosec research community, and we would like to work with them." response might have been more appropriate.
That's just my personal impression, though.
edit: autocorrect fix
