It is kind of ironic that a lot ace bloggers defend the use of allosexual on the basis that non-asexual would be too "othering", since allo- literally means "other". Take for example, "allograph", which means "written by another person". allo (from Greek allos / ἄλλος, meaning other) + graph (from Greek graphos, meaning writing). Like how are you going to argue that one term is too "othering" when your preferred term literally means "othersexual" / "differentsexual".
non-ace isn’t even othering. you can attach non- to any word ever and all it does is specify those who “are not” unlike allo which, as you said, is a prefix that literally means “other”