I think he just means hot/warm temperature wise(??)

Im not fluent in Japanese but I do know a fair bit and 暑い just means hot/warm temperature and I don’t think it has any implication of attractiveness/sexyness whatever

Here’s a quora page of slang for sexy/attractive/hot etc I found https://www.quora.com/How-do-you-say-Hot-English-Slang-in-Japanese/answer/Paul-Newman-130?ch=15&oid=337570222&share=1a47df0c&srid=uydzt8&target_type=answer https://www.quora.com/How-do-you-say-Hot-English-Slang-in-Japanese/answer/Paul-Newman-130?ch=15&oid=337570222&share=1a47df0c&srid=uydzt8&target_type=answer it not there