What Andersen changed was the command line argue for default_block_size. What your discussing through out the article is max_block_size which has been 1MB since Jul 14, 2010

https://github.com/bitcoin/bitcoin/commit/a30b56ebe76ffff9f9cc8a6667186179413c6349

(note the commit notice isnt very clear but you can clearly see in the diff that it was added)

It was ported from source forge and was implemented longer then most of the people mentioned were involved on the project

I could send a 1MB block in this setup and it would processed properly, even with the default being different on the miners.

I think important to get this fact right because the narrative should be “someone put 1MB to put prevent DDOS attacks” (as you noted) but was never revisited as the code improved. not that “it was incrementally revisted until X party showed up”

Bitcoin Classic changed max_block_size and so has every big block fork size.