The avian doing the double tapping would quickly become landfat and as such become more open to mass ops. While the avian who got double tapped can hit back with an ambush + a trad march, all the while having a huge boost in TPA prowress. A hybrid avian A/t doesn't need to rely on economy based buildings nor aid from fellow kingdom mates in the event of being chained, simply due to the increased TPA, which also allows you to rob pretty much everyone around your networth at that point. Its all situational anyhow.
Also since you don't have to pay wages for thieves, you can maintain a slightly higher draft than a heavy attacker.