Nice argument but did you consider letting someone beat up a sleeping Pokemon is a tactic in videogamesAsh just standing there while Dragonite got sucked off by Dream Eater was the equivalent of standing in the middle of a busy street during rush hour. It's not about plot armor or lack thereof, it's about Ash lacking common sense all of a sudden.
And don't give me that "Dragonite wouldn't wake up in his Pokeball" argument. Yeah like no **** he'd still be asleep in there but there would at least be a chance Dragonite could've woken up while on the field later on if sent back out later. But we'll never see that because Ash ****ed up.