Dr. Sit (again) and Elder Tsui - why did these guys seem to hate KF more than most?

Throughout the persecution of Kiu Fung, I felt that two wulin members were conspicuous in their absolute condemnation and hatred for Kiu Fung: Dr. Sit and Elder Tsui (of the Beggar's Union). At the time, there was still some lingering doubt among many members of wulin (e.g. Kiu Fung's fellow Beggar's Union brothers and some of the Shaolin monks) about whether Kiu Fung was actually of Khitan heritage and whether he had actually committed the murders of which he had been accused. Elder Tsui and Dr. Sit, however, seemed to really have it out for Kiu Fung: both of them were absolutely, 100% convinced that Kiu Fung was Khitan and a murderer, and didn't entertain the idea that perhaps Kiu Fung was innocent.

Elder Tsui, I can kind of understand: he seemed bent on purity in the Beggar's Union, and didn't want the shadow of a possible foreign enemy and murderer to serve as Beggar's Union Chief or be a menace to wulin. There might even have been some latent personal desire to be Union Chief himself (though I doubt it). I cannot understand Dr. Sit's fervent hatred of Kiu Fung, however. He had never met Kiu Fung until the Tsui Yin Manor conference, and everything Dr. Sit knew about Kiu Fung was anecdotal. Even so, this respectable doctor, famed for his compassion as well as his supreme medical skill, initially refused to treat Ah Chu's injury simply because it was Kiu Fung who brought her to him. What could justify or even explain such hatred for Kiu Fung in Dr. Sit?