Co-Bathing with dad?

So I had a conversation with my mother in law ( she's a bit off her rocker ) & I was telling her that when my son gets here I will be co - bathing with him because it's a very close bonding experience and she said that was okay , but when I started to say that my sons father ( my fiancé and her son ) will also co - bathe with my son on the days I'm at work and he's home , SHE STARTED TO FREAK OUT! She started ranting about how wrong that was and how it's only okay  if I do it because I'm a woman and "he's a dad and dads shouldn't be bathing with his kids" 😳 like are you f****** kidding me ? The nerve of this woman .. I had to walk out and clear my head after that conversation to make sure I didn't go crazy and let the hormones get to me ! My question is , how many people out there think it's okay for BOTH parents INCLUDING DAD to co bathe with there kids ?