You left out the full argument (to be clear, I don't agree with the author, but in order to disagree with him you have to quote the full argument):

The author is arguing that the main reason rewriting a C++ codebase in Rust makes it more memory-safe is not because it was done in Rust, but because it benefits from lessons learned and knowledge about the mistakes done during the first iteration. He acknowledges Rust will also play a part, but that it's minor compared to the "lessons learned" factor.

I'm not sure I buy the argument, though. I think rewrites usually introduce new bugs into the codebase, and if it's not the exact same team doing the rewrite, then they may not be familiar with decisions made during the first version. So the second version could have as many flaws, or worse.

The argument could be made that rewriting in general can make a codebase more robust, regardless of the language. But that's not what the article does; it makes it specifically about memory safety:

> That’s how I feel when I see these companies claim that rewriting their C++ codebases in Rust has made them more memory safe. It’s not because of Rust, it’s because they took the time to rethink and redesign...

If they got the program to work at all in Rust, it would be memory-safe. You can't claim that writing in a memory-safe language is a "minor" factor in why you get memory safety. That could never be proven or disproven.