There is no reinterpretation going on here. Apple never asked the EU. Apple went to Ireland "hey, guys, do you think it is okay to do this?" .. Ireland said yes, but Ireland has no authority here. The EU, which has authority, checked it and said "nope, your interpretation is wrong." - Simple as that.

If I ask someone on the street if its okay to steal from the rich, he says "yes" and I steal from the rich, no one would bat an eye if the courts didn't agree with my "interpretation" of the law and put me behind bars. And no one would accept it as a legal defense if I said "but hey, that guy over there said it is okay to do this!" - why should it be different for companies?