Personally....I think it needs the jetpack. It has the look and feel of an outfit that should have the same jetpack as the the hunter and same unlock requirements. and while were on the subject of flying, how come the angel costume for huntress doesn't have the ability to fly?
Well in order to unlock the hunter outfit we had to beat all campaign on nightmare, so what about doing beat wave 14(or 25) survival nightmare difficulty for all campaign missions and lost eternia shards missions, but require that in order to obtain the unlock you must start on the lowest wave possible. That would prevent people from just starting on wave 13 or 14(or 23/24)and unlocking it too quickly.