In a fair, straightforward martial arts fight, Kiu Fung would almost certainly annihilate Ding Chun Chou. Everyone knows, however, that Ding Chun Chou never fights fairly. He uses poison and unorthodox tricks such as his Force Dissipating Skill to overcome his enemies. As powerful a fighter as Kiu Fung was, he had no immunity to poison. Kiu Fung's inner power was higher than Ding Chun Chou's, but Ding's Force Dissipating Skill was different from the Siu Yiu Sect's Bak Ming Sun Gung or the Force Absorbing Skill later seen in STATE OF DIVINITY; he was not absorbing the enemy's inner power so much as he was dissipating it, so I'm not sure that the limitations of Bak Ming Sun Gung/Force Absorbing Skill where the user's inner power must be higher than the victim's apply to Ding's skill. If they don't, then this skill would be able to dissipate Kiu Fung's power as well.
The trick is that to apply poison or use the Force Dissipating Skill on Kiu Fung, Ding Chun Chou would need to get within physical proximity to Kiu Fung. Being the coward that he is, Ding Chun Chou is unlikely to put himself at such a risk: even if he succeeds in using poison or Force Absorbing Skill to injure or kill Kiu Fung, Ding will likely end up himself being killed by Hong Lung 28 Palms.