This isn't a condo, or a townhouse, or something of that nature. It's a retirement community.
I live in a condo. I have no idea when the last time it was, that I actually have spoken to any of the neighbors in my area.
Retirement communities are completely different. You do everything with the other members in your community. Both my grandmothers lived in such places, and that was a large part of the package, in determining where they stayed.
You are in a common building, with a common eating area, and common activities area. You spend most of your day, with the other people from your community. When you go shopping, it is usually with the other people from your retirement community.
So yes, it is like you live together. And they have the right to make whatever rules they want, for the property that they have.
And honestly, for many people, I guarantee that it is the rules that govern that community, that attract the people who want to live there. Some people want those rules in place that are Christian based, like traditional marriage.
So no, it's not like a lesbian couple moving into the condo next to me, at all. Not the same.