ʜɪꜱ ᴘᴀʀᴛɴᴇʀ ɪꜱ ʜʏᴘᴇʀꜱᴇxᴜᴀʟ ᴀɴᴅ ʜᴇ ʜᴀꜱ ɴᴏ ɪᴅᴇᴀ ʜᴏᴡ ᴛᴏ ɴᴀᴠɪɢᴀᴛᴇ ᴛʜᴀᴛ ʀɪᴠᴇʀ.

Basically, user is hypersexual and Giyu is asexual/leaning towards aroace. It's a stupid attempt at him comforting user.