Citation desperately needed. Here's a contribution from literally the day before he had his commit access stolen.
https://github.com/bitcoin/bitcoin/commit/006cdf64dc932
Even if he did say that, it's irrelevant to this discussion. Him "no longer contributing" was not the reason his commit access was revoked. It was revoked as a power grab because he wanted to and had the power to increase the block size. Nothing more.
Citation here BTW: https://twitter.com/notgrubles/status/1247592193319198720
Yes I agree this was the public justification for it. That being said, I'm certain they wouldn't have acted in the same way if it had been Luke jr or Greg Maxwell. They pulled his access because he wanted bigger blocks and he was ruining the official narrative.
I believe your citation but the point still stands.
And for future reference, a citation isn't generally accepted when it's just a screenshot you posted in a tweet you once made where the screenshot reveals a comment to a random reddit post with no visible url in it.