He said it's one of the obvious things to remove if you're trying to make a faster, more static language. And apparently he got Brendan McArdle to implement this list of features, and the resulting language was 10x faster on some toy examples. It reminds me of the hiphop talk where they list why PHP is slow (https://youtu.be/p5S1K60mhQU?t=634). Of course Facebook then went on to release the Hack language.

But it's not clear to me that he'd necessarily remove these features in an R clone. For example, eval is one of the features to remove. Python has eval, and I think many people use it, because it's convenient. Although it's hard to implement in a static language, that isn't a good reason to remove it in a dynamic scripting language. A PEP to remove it would probably get shot down immediately.