Note the word 'advised'. This is a legal opinion from an important individual who looks at the case and tells the court what he thinks. But (i) the court can ignore it or look at the case themselves and make their own opinion; and (ii) any ruling they do make does not bind any EU government to implement it (though it should strongly decisions in EU countries). It's like asking your mechanic friend what he thinks of the car you've got lined up to buy.
As the CJEU press release states:
> NOTE: The Advocate General’s Opinion is not binding on the Court of Justice. It is the role of the Advocates General to propose to the Court, in complete independence, a legal solution to the cases for which they are responsible. The Judges of the Court are now beginning their deliberations in this case. Judgment will be given at a later date.
http://curia.europa.eu/jcms/upload/docs/application/pdf/2016...