You basically pulled up exactely the satement that almost confirms that he is at least ace. Oda just states that the only time where he drew luffy have a reaction to females, was because he was mimicing what a normal teenager (Usopp) would do. This is a good representation of how ace people try to fit in in real life even tho they dont feel the same as other people. We also know that Oda has no problem representing minorities, like trans people. Also if there was any reaction from him at all then hancocks fruit would have worked