my friend’s mom says i can’t paint my nails

i (m) started painting my nails recently and my friend (m) wanted to see a picture so i sent him one. his mom apparently goes through his phone pretty often, so she saw that photo and told him that we can’t be friends if i continue to paint my nails. personally, i don’t think it’s right to dictate who your kids should be friends with and is also don’t think it’s right to tell someone else’s kid what’s right and what’s wrong. i came to this subreddit because we are both christian and r/teenagers probably wouldn’t give the best answers.