Apple isn't beating its green chest about the production process. This is about data centers, not production.
You need to look at the whole chain in order to be able to make a judgment on whether it is better for the environment or not. And you lack (and so do I, but I regularly work in manufacturing of diagnostics equipment) information on Apple’s production process.
They might shave off 90% (although this seems too much. Where did you get this information?), and I agree that re-using shavings is energy intensive. However production of plastics and molding plastics are also very electricity and water intensive. In addition, plastic casings are produced in more parts than unibody chassis, which increases energy consumption. Moreover plastics are more polluting and more difficult to recycle. Another factor that needs to be taken into account is the reclaim value and lifespan that the product has. Aluminium is easier to recycle and Apple does have a recycling program in place (where are Samsung’s, Lenovo’s etc?) to increase the reclaim of those products.
Other factors that come into play are supply chain effects such as transport of parts etc. We don’t know a lot about the production process. There is no way that you are able to make a statement that Apple is more or less polluting than the rest without more information.
Last but not least it would also help to differentiate your argument better. Apple is here advertising its efforts in clean energy generation for data centers. They nowhere speak of their production process.
You need to compare