Serious LN dev is hard and time consuming, I no longer have time or resources to keep it up or even maintain what has been developed so far. In my opinion the whole LN protocol is overly complex and is getting worse and at this point can only be developed by very few high profile specialists at a very slow pace.
That probably sums up his real objection 100%. Lightning is just too complex for his skill set, and he's angry that he's being pushed out of wallet development because of that. Meanwhile Lightning is a success, and adoption of it keeps going up, pushing out on-chain Bitcoin stuff. Which also pisses him off.