It's not evident from Andy Wingo's blog post, but just to clarify, Gerry didn't choose Python over Scheme: a committee did. Gerry said that when they had their revelation about the state of computer programming in 1997, he and Hal Abelson decided to stop teaching 6.001, and they eventually stepped away from the course altogether. (I believe Gerry returned to teach the class for the final term it was offered, but he didn't get into that last night; I could be wrong.)
Gerry went on to say that 6.001 essentially languished until sometime around 2007, when a committee got together and redesigned the introductory EECS curriculum to be what is now 6.0[012]. He didn't say whether he was on that committee, but I got the impression he was not. He appeared to be speculating when he offered the reason why Python was chosen. It was an offhand remark, something to the effect of (and I'm paraphrasing here), "And why Python? I suppose there were already good libraries for controlling these robots."
It sounded like Gerry explicitly chose not to fight any battles at all on this issue, and simply walked away resigned to the fact that computer programming, and engineering in general, are much different now than they were when he, Hal and Julie wrote SICP.
Two more things:
* I don't recall Gerry using the word "practical" even once while reciting his short anecdote.
* Gerry continues to teach with Scheme, not Python, in 6.945, his advanced topics course.