I have two issue with that.
First, someone would have to work very hard convince me that recycled plastic or not, those flakes aren't specifically tinted to look exactly the way Apple wants them to.
Second, and that's the important one, as soon as recycling becomes a fashion statement, the question about effectiveness begins to evaporate. Or more accurately, impossible to bring up without giving off the impression that one is against improving the environment. As soon as the important part becomes that things "look recycled", that's what the market will deliver, whether the thing is actually recycled in a way that provides benefit or not.
And who knows if the environmentally best recycling methods won't soon actually produce something that looks "cleaner" and thus looks "worse for the environment" than some faux recycled bullshit product.