Easy there, killer. It was (mostly) a joke.
Though, to me, at least, a girl talking to a guy about someone they like if they've been somewhat led on like he says he feels like he may have been doing is probably not always the best course. I would imagine it's the same across both genders. If you've led someone on, suddenly saying "yeah, I like so-and-so" would probably be a bit of a smack in the face.
I haven't really been in that position more than once. I accidentally did that and just flat-out told them, look, I didn't mean to lead you on, but I'm not interested beyond that. I always try to make it abundantly clear to most friends what my intentions are from the start so I can avoid awkward situations in the future.
In my case, I'm relatively certain she appreciated the honesty and me saying "my bad". I certainly think she might have been upset had she been led on and then I just suddenly started talking about who I liked to her.
Might be a decent course of action if the leading her on thing hadn't happened in his case, but he thinks he led her on, so I don't know if that'd be the best way to go about it.