She LOVES it. And, no, she has not gotten hurt and is not scared.
He will push her limits a bit, but does respect her wishes to stop if she asks.
You want him to respect your wishes and parenting you need to do the same for him.
Some times we have to turn our heads. I am afraid of high dives. I admit my fear and tell my kids I can't watch them but will take them to do it.
My dh can't swim and was terrified of water. He went through years of panic attacks learning to trust me and that I would not put our children in "real" danger. He had to learn to trust me, then my kids, judgement on water activities.
I think sabotaging the swing is wrong, dishonest, and manipulative . Wouldn't disagree with changing the swing seat if the seat is old.