I thought that the EU court had already ruled that even if the purpose of moving was to exercise your treaty rights, as long as you met the other criteria (3 months, centre of life) that was fine.
In fact, the draft deal states:
‘In accordance with Union law, Member States are able to take action to prevent abuse of rights or fraud, such as the presentation of forged documents, and address cases of contracting or maintaining of marriages of convenience with third country nationals for the purpose of making use of free movement as a route for regularising unlawful stay in a Member State or for bypassing national immigration rules applying to third country nationals.’
So it very much sounds like they want a change here, implying that at the moment bypassing national immigration rules is acceptable.
Later it states:
‘Member States can address specific cases of abuse of free movement rights by Union citizens returning to their Member State of nationality with a non-EU family member where residence in the host Member State has not been sufficiently genuine to create or strengthen family life and had the purpose of evading the application of national immigration rules’
Emphasis mine. That "and" is very important, as it implies you would have to fail both the centre of life test and be shown to be done to evade national immigration rules.
It's all a bit confusing. It also says:
‘to exclude, from the scope of free movement rights, third country nationals who had no prior lawful residence in a Member State before marrying a Union citizen or who marry a Union citizen only after the Union citizen has established residence in the host Member State. Accordingly, in such cases, the host Member State's immigration law will apply to the third country national.’
Which would seem to imply and end to the SS route for most people. Urgent clarification is needed, but I can see many people (including myself) forced to leave the UK because of this.