Luffy's attack on Magellan during their first fight seemed to be pretty effective on him. The difference this time, however, is that Luffy never went into gear 2nd. All logia users have a passive defense that makes attacks pass through them. BB explicitly stated that he is the exception to this. There has never been an instance where Magellan physically turned himself into poison, and even when he's traveling around, he just uses his poison as a chute to slide across. None of these behaviors point to Magellan being a logia type.