I think all things considered Erik you handled it pretty well and there wasn't anything you could do or say short of out right and blatant lying to make dad happy. I probably would have been a little snarkier myself so you did a good job trying to toe the line in my opinion.
It's still a good lesson for your daughter in sportsmanship and doing the right thing. I talk with my daughter about things like that and parents such as that and tell her that what's okay for them is not okay for us, we do what's right and compete fairly even if we know others sometimes may not.
Dad sounds like a dick and he isn't doing his daughter any favors in the long run.
There's a Little League field that has a sign to parents that says there are no college or pro scouts here today so lets just let the kids have fun.
However a strike is a strike and a hits a hit. One team wins, another loses. I don't understand the everybody wins mentality we have for kids sports. It will not serve them well when your competing for a promotion later in life.