It’s still easier than if you had never previously written an if statement. If there weren’t a lot of differences between languages then we wouldn’t have so many languages, but that doesn’t mean that there are not a lot of concepts that are used widely across many languages.
However the more languages you know and the more they're spread across different paradigms the shallower the learning curve will be for any language one wants to pick up.
Be fair to the original comment, which referenced people saying something about learning a language, and it making learning any others easy, not about learning many languages, and it making learning any others easier.
Writing Python in Rust unlike say writing C++ in Rust, might actually be a desirable thing. Put it this way, It will be a while before you are writing Rust like Python.