Politicians are rarely appointed on the basis of skills and expertise, and mr Harper goes to great lengths to prove he is no exception to the rule.
All measures he wants to impose on EU nationals are illegal, unless they are also imposed on British nationals.
For example:
I don't now the details about Spain, but in the Netherlands there is the GBA (Common Population Register) and everybody (regardless of nationality or status) living in the Netherlands has to be registered in there, and any change in the registered details (such as address) has to be reported within 5 days. In essence this system was introduced by Napoleon, and so it exists in most countries that were under Napoleontic occupation.The idea was first raised by Philip Hollobone, the Conservative MP for Kettering, who claimed the Spanish already "interpret the free movement directive much more robustly" by requiring all European Union citizens and family members to register if they want to live there for more than three months. They also require notification of any change in address or marital status.
In the UK there is nothing like that, and therefore it cannot be imposed on EU nationals either. It has nothing to do with a robust interpretation of free movement; it is simply about treating EU nationals as your own citizens.