BlackHeart Biohazards

AITA for engaging in nsfw fandom topics with someone who recently turned 18?I (22F) have known my friend (18NB) for 3 years. We used to write meta essays for the fandom we were in together, and had a lot of back and forth about characters/themes etc. All of it purely sfw. Last year they turned 18 so I gave them access to the nsfw channel on our discord server. They’ve shared art, headcanons, etc. About different characters, and I’ve provided my own commentary on that. One of our mutual friends (24F) is uncomfortable with me letting the younger friend into the nsfw channels because “we’ve known them since they were 15” and it’s “inappropriate” because we’re so much older than them. To be quite honest, they’re 18 now, and it’s not like I’m talking nsfw to/about them, it’s about whatever characters, so I really don’t see the issue. 24F called me a “groomer” for “waiting for them to turn 18 so I could talk about nsfw stuff”. I have never once sexualized 18NB, so this got me really upset.