to be honest, it does depend.
I wouldn't take my own kids, because they have access to a garden so it would be completely inappropriate for them to steal the space.
That said, I do feel a bit sorry for kids without garden, who have been cooped up at school all day and enjoy a bit of splashing on the 2 hottest days of the year. I would find it hard to tell them to go. Maybe ask the park to schedule another session this month, to give the SN kids another chance to play too.