Let your daughter sleep at her friends house ?

When that friend has a single father ? My daughter had been asking daily to have a sleepover with a new friend at school. And well first of all mom, dad, aunt, grandparent she can't sleep out where I don't know the family. We Finally saw her getting picked up at school today by her dad and he sounded like he was the only parent home. He mentioned it's a little weird because it's always moms. Which made me feel bad she probably doesn't get a lot of play dates because moms want to hang with moms. He offered for us to just come hang out a few times and just get comfortable at their place. I took his number down and told him that her dad can also come hang out with them if he feels more comfortable. When I told my friend she said she would never be okay with it if it's just a dad. But I work weekend nights so also any girl coming to sleep here would be with my SO from 5-11 at which time the 7 year olds would be asleep anyways. I have full confidence my SO wouldn't do anything to any little girl but I guess I would also understand if the parent wasn't comfortable ? A pedophile will be a pedophile married or not so how can you ever be sure ? I can't go through life terrified. Would she feel differently if she had any boys ? Can a boy sleep at a house with a single dad ? This is very confusing for me. My daughter is only in first grade and hasn't had friend sleepovers before but sleepovers were some of the most fun times I ever had as a kid, I don't want to rob that because I'm scared of everyone. How would you ladies handle this ? (The point is kind of moot though if you don't let your kids sleep out at ALL. Because I don't plan to make that a rule.)

Edited to add: I agree that he's done nothing wrong by being male. I agree that she is probably missing out because other moms who feel the same as my friend. And if you read my post I don't think you would get the impression that I have anything against him. I certainly love the opinions coming in I feel much better, but please stop accusing me of thinking negatively about the guy because I think I gave opposite implications.