Not for me to answer, I'm not a proponent of the change. I'm sure if you read past discussions here and on Discourse you'll find answers from the people who studied the problem carefully.
The opening mail proposed C++11 without rationale or references. I did search the archives and discourse before, but nothing stood out, and I don't think an encyclopedic knowledge of past python-dev discussions is a reasonable requirement to comment or propose a variation on its merits.
I thought you might have something to add to the conversation, but I guess not?
I find this tone quite out-of-place. I made a proposal (based on compiler support, version hygiene and compatibility with newer standards), and I'd have been more than happy to hear arguments (like Antoine's) or references for the merits of preferring C++11 (though, again, the point became moot since Victor correctly pointed out we can test against several versions). Still, the insinuation (as it arrives on my end) that I shouldn't participate seems really unnecessary. Best, H.