Raymond Cobsend had been a thorn in Khan's side since Milia 222. The man was slippery, resourceful, knowledgeable, and capable. He was always one step ahead of Khan, earning benefits without ever having to face proper punishment.
Luke had tried to help Khan catch Raymond, but to no avail. The latter always reappeared with a new offer, which he often saw fulfilled. It seemed Khan had played into his hand the whole time, and Prince Thomas' ploy was only the last of the attacks on his persona.
Clearly, Khan couldn't deal with Raymond on his own. He didn't lack resources, power, or knowledge, but Raymond kept beating him. Khan wanted that trend to end but didn't know how.
According to Prince Thomas' story, he had been the closest to catching Raymond without giving him any benefits. That was more than Khan could claim to have ever achieved against Raymond.