I actually really disagree with this. Python and Ruby are extremely similar in the problem they solve. If you're using MySQL as a basic OLTP database, and you need a basic OLTP database, you shouldn't use Postgres.
I'm talking organizationally here, not just on a single project. You gain nothing by introducing Ruby to your company that's filled with Python experts. Instead, you introduce a bunch of friction and overhead as developers have to relearn things like syntax, how to set up their development environment, how to do dependency management, testing frameworks, etc...
The time to introduce new tech is when it is fundamentally different enough that it could matter. Maybe you have a bunch of Python code, but there's a certain area that's very performance sensitive: you could look at using Rust, Go or C++. Maybe you have MySQL, but you need a database that's used for complex OLAP queries rather than low-latency OLTP work. There you could look at Redshift, Snowflake or the various Postgres OLAP configurations.
Where experience comes in is knowing when these new tools are worth the overhead they cause. Less experienced engineers vastly underestimate the overhead that comes with introducing new tooling. This even applies internally; for example, if you've used Flask for every project you've done at your company for the past 5 years is it really worth switching to Django?
I think you agree more than you realize. GP is essentially saying there are few situations where you will be deciding between Python and Rust on account of organization and technical reasons. However, sometimes you should consider introducing new technologies, but only when you identify that the problem being addressed is much better solved by a new technology, fully aware that this will cause various sorts of friction within your organization.
If your main product is C or C++ then you should be learning about things like rust. Maybe you decide modern C++ is good enough, but if so you should be working with the C++ committee to push safe C++ (as a C++ developer I'm hoping this comes in C++26... I'm looking at how I can put rust into my code for now).
The point is you should know what the good next steps to investigate are and what are not. Rust and Python are both great tools, but it is never okay to choose between the two on any project - the choice is obvious before you get to choosing. Both tools have other competitors that you perhaps should be looking at though (Rust - ada, C++. Python: ruby, go)