I don’t think it’s a debate on the dictionary definition of free time as much as it is philosophical one to decide how one choice fundamentally differs from another in OPs scenario. You join a bowling team and bail on them one weekend and you’ve let your teammates down. You leave your kid with the in-laws one weekend to go on a romantic weekend getaway and everyone benefits.

I would argue that there’s no fundamental nobility to raising kids as long as you chose to have them, and I’d also argue that time spent with the family you chose to have absolutely counts as free time.