Explaining it does not make it fine. No matter how it’s coded, flight and hover is a buttonpress ability and there should get disabled when hacked.
If you want your mind boggled further, by the way, here’s an orange post saying that Echo continuing to fly when hacked is intended:
She is if you set it to “hold to fly” in her options menu. I think many people do it that way because it’s easier to do glide slingshots like that.
Neither is Pharah’s hover, Mercy’s angelic descent, or Lucio’s wallride.