Nothing on that form contravenes the Act.  The exemption will be recognized after the form is submitted and the eligibility is verified based on the supporting documents submitted.

Just because the spouse can elect to file as NR doesn't mean the employer has authority to retroactively refund taxes that have been withheld to date, which is a matter governed by state statutes and there's nothing in the Act (before or after the amendment) that compels states to do so.  The spouse would simply file an NR return to claim a refund.