It wouldn't have been easy to get the Hunter Association to support him. His S-Rank Hunter status wasn't enough for that. After all, there were two more S-Rank Hunters in the country.
Moreover, his only appearance as an S-Rank Hunter was towards the end of the recent raid, so his status wasn't yet concrete enough.
But that is where Ying's new nature came into play—Compass Carburettor's merchant mind.
He contacted the Hunter Association President and sold him one Elven Tear. The President was once an S-Rank Hunter. But now, he was gaining in on age, leading to a decline in his strength.
So, when he was presented with an Elven Tear, the offer was irresistible. The Hunter Association President had no other choice but to bite the bullet. The Elven Tear made him younger by a couple of decades, allowing him to regain the power of his prime.