Recognizing that the exposure myth of Romulus and Remus is an analogue of the exposure myth of Moses, of Cyrus, and of a host of other famous figures gets one thinking that early Roman history and early Jewish history, among others, map common Eurasian stories onto particular agendas.
Or perhaps its because infanticide via exposure was a very common and widespread practice for most of human history.
Either way, there's a large gulf between "Romulus and Remus weren't real" and "Romulus and Remus weren't exposed as infants." You obviously don't believe Cyrus is fictional.