Imagine how he felt when ZeWu-Jun told him about Wei Ying's love confession and then having to find out his best student ran off and eloped with his worst. Probably bout Qi deviated and fell over dead.
He was so frustrated he made a new rule or at least forbade anyone from interacting with WWX. I think spitefulness is against some GusuLan rule. Poor guy was seeing his brother all over his nephews
Lan QiRen is one of those people that really only follow the rules when they suit him, so frustrated that he made quite a few rules against. Nevermind that Wei Ying, Lan Zhan, A'Yuan and JingYi just ignore the more spiteful and ridiculous ones but yeah pretty sure that being petty and spiteful are against the Rules...
Imagine how LWJ must have felt learning about the lengths his uncle, literal father figure, took against his beloved. Still not as bad as what Madam Lan got, but yeah. He can punish the juniors all he wants, it won't stop them from flocking around WWX
Remember that even before they returned to the Cloud Recesses they learned that the A'Yuan, JingYi and the rest of the GusuLan juniors where night hunting with Wen Ning and we're being punished for the third time and they just made sure to interact with Wei Ying out of the eyeliner of anyone that would punish them for it. I really doubt that he cared too much what Lan QiRen thinks about his beloved after realizing that caring to much about what others think especially if those thoughts/actions/words is detremintal in more ways than one is no way to live especially if ulterior motive is involved and don't forget that that old mountain goat joined the lynch mob both times despite the fact that there are many rules against that kind of thing. Wei Ying gained the trust of the Junior Quartet and probably most of the younger generation with actually trying or even meaning to, he even won over A'Ling who had sworn to hate him because of all the lies that he had been fed since he was old enough to understand and had dreamed of mutual assured destruction until he started to realize what was going on and then got the truth that Wei Ying was a scapegoat for his xiaoshu's machinations.
And just imagine if Lan Qiren was there. He would need a fainting sofa if he were to walk in at *that* part of the chapter