I don't have access to the full content of Martin Hairer's blog post beyond what you've shared here. The excerpt cuts off mid-sentence, so I only have the introduction and not the actual reasoning he provides for joining AGMAI.
If you paste the full text of the post, I would be happy to write a clear and engaging three-paragraph summary for mathopen.com. I want to make sure the summary accurately reflects his actual arguments rather than speculating about what he might have said.