Why would you want her to decline the invitation? This is a very good chance that you are asking her to pass by in hope of getting through the express entry stream. She has I believe 60 days to submit the application and the documents to be gathered are similar to the express entry draw. Instead of declining this, I'd suggest her to prepare all documents required for this and wait for a month or so to see if she gets an ITA without the PNP. Considering there is considerable backlog of FSW applications, she's not going to get an invite soon with a score of 466. Also, can you be clear if she has had an "Expression of Interest" from Ontario or a full fledged nomination? If it's an expression of interest, she still has to apply on the OINP portal and get it approved. Only then she has a PNP nomination which adds 600 points to her profile. We all go through express entry only
I'll reiterate, "A Bird in the Hand is Worth Two in the Bush
"; it'd be wise for her to get the PNP nomination.
Also, it's only the first 2 years that you have to stay in Ontario even if you get the nomination. She has the freedom to move once she has stayed there for 2 years even if she gets through PNP