I would find that strange and borderline misleading for them to reject 5 points given their own provincial requirements. Furthermore, family ties does not directly or indirectly mean you will adapt better especially when you are an adult with your own children. Their statement didn't mention ties in Ontario. It mentioned that you had family in Canada. My family can be in Nunavut today and move to another province by the end of this month. If this has another meaning, then the province needs to update their requirements and explicitly state it like the other nominee applications. I say, give the man his points and get on with it.
I just hope that CIC doesn't become sloppy like the US during these immigration processes.
"Relatives in Canada
You or your spouse or common-law partner have a
relative who is a Canadian citizen or permanent resident living in Canada aged 18 or over. The relative can be a parent, grandparent, child, grandchild, sibling, aunt, uncle, niece or nephew."