This post is not about being acuhired at all. Read it again. His main thesis has been in the last couple of blog posts is:

Social media platforms should not be ad-supported.

This is just a continuation of that theme. He's saying, ~Your employees are doing asshole things to 3rd party developers, even though you're calling it a platform, because they have bad incentives, and that bad incentive is coming from the search for ad revenue~

Essentially, he's not so much mad at Mark, or even really caring whether Mark reads it or not. This is another piece of proof (to him and others that might listen), that social media platforms should not be ad-supported.

"The only way to get fulfillment is to help other people that believe what you believe." - Simon Sinek

You should watch the TED video where Simon Sinek talks about this. Dalton is basically putting this crazy idea out there about a non-ad supported social media platform (gasp!), and trying to find people who believes what he believes.