In I-land Sunoo was the outcast and dark horse.....
The only reason he got through is because he has a huge solo fandom that would vote really hard for him, that's what made him the extra pick
For people who didn't watch the show Sunoo was the member who was always voted grounder by the other trainees.
This is why the groups dynamic is always weird and rubs people the wrong way, Sunoo was never the person the other members wanted to debut with and personally I suspect jealousy had something to do with it.
Sunoo was also never liked by the producers but because of his popularity he was picked as the producers choice.
With these reasons of course his fans will feel very protective over him considering what he went through.