You don't win by only defending. Likewise, you don't win by only attacking. A rabid dog might take every chance to snap at any perceived vulnerability, nipping and ripping at any open emotional wounds. In time, people will avoid that dog. They'll stop it. Light's reasons for doing anything are often complex, but if looked at through a harsh lens, he gains nothing by taunting L. Distance isn't his goal. That isn't to say he'll always be a saint, but he won't always be a sinner.

"It's his sword and his shield. I didn't spend a lot of time with him, but I could tell that. It's complicated with him."

Niles is a pervert, but the way he wielded that perversion wasn't the weapon of someone who enjoyed the act and simply wanted to engage in it as much as possible. It was used to try and make Light uncomfortable, perhaps even judge him a bit.

The rest of L's reply is no surprise. Their time together here has been comparatively short, but Light didn't sense any kind of uncontrolled lust brewing behind midnight eyes.

"I'd have to be surprised to be relieved. Unless the change happened since I saw you this morning, I can tell you're not suddenly controlled by it."

Which is good. Light would have been disappointed if his rival, one of the greatest minds of their Earth, suddenly began to think only with another part of his body. It would be like opening the most beautifully wrapped present to find an annoying toy.

"I think it's possible to feel lust and to choose when to indulge and when to reject. It only controls you if you let it."