He'd be right; decompression sickness is a fascinating but really nasty condition. Who knows how mermaid biology or story magic counters likeliness of getting the bends, but better safe than sorry.

"Than'gyu... And... no, THING zhould be fide..."

It's just straight up, right. Although if she does end up needing help, the won't say no... although he should be careful he doesn't make her nose bleed more~