No.
SKT would never risk to be disqualified or to ruin the feeling of winning worlds, by cheating for such a silly thing.
SKT has beat RNG twice already, I don't think they're that afraid of them.
Also, RNG didn't qualify because of RNG. If they proved they were better than FNC in that BO1, they would be qualified, it was 100% up to them to win that game.
And it's not like SKT was that desperate for the cash prize.
You also need to consider the fact that if Kkoma proposed its own players to cheat, the relation of trust between them would be broken.
How can you trust someone that's ready to cheat ? It would ruin things, and I doubt he has such a low morale to do this.