Well, duuuuh.
I kinda get the argument. Nobody wants to spend time maintaining the tools they use to make other stuff, but the tools written in Python by Python developers are likely written that way to be useful, maintainable and in a language they're productive in. Immediate time is an important expense when you're writing tools.
You talk about sunk costs, but sinking time into becoming as proficient in (eg) Rust as Python seems ridiculous. Especially for smaller tools.
And why are we picking on Python? Javascript toolchains eat themselves every 18 months. Yeah Python versions upgrade but we're going to pretend that Node doesn't?
If you don't want a fight, don't pick one. Let developers use their own expertise and experience to decide what they use.