You know it's never safe to bring unrestrained birds outside... and harness training would solve your issue. Yes, it may take a long time, but it's worth it to be able to SAFELY take your bird outside while keeping his flying abilities. And if a bird is so bonded to you, why not teach him to fly to you? My birds are recall trained and fly to me on their own, just to be with me. Plus I saw that photo and it looks like he has about 5 flight feathers trimmed, my conure has 5 feathers trimmed on each wing (the breeder did it) but he can still gain a good amount of lift and fly around fairly well. Not as well as my budgie and cockatiel, but still enough to fly away if I took him outside.