1. If 'arsenokoitai' is the "aggressor" in a homosexual relationship and 'malakoi' the "passive" partner in 1 Corinthians, why is malakoi absent in 1 Timothy? An arsenokoitai would be missing the other half of his relationship. If they are a word pair, no other vice list with either malakoi or arsenokoitai, and there are many with malakoi prior to Paul and many with arsenokoitai after Paul, ever have them paired together.
2. If 'arsenokoitai' can be the catch-all word for both sides of a homosexual relationship, why does Paul bother using malakoi in 1 Corinthians? "Koites" was used centuries before Paul's usage and when used as a suffix in compounds it always indicated the penetrative aggressor, never the passive. That means it can't apply to both partners in an act and cannot be a catch-all term for all homosexual activity.