I actually don't like Python and much prefer Java, but I think #3 is really only for performance research and like, fun and games. It would be cool to have a quantified answer to "just how slow is Python"? I suspect the answer is many orders of magnitude slower.

However, if the experiment in question is, "using python glue code, can a developer string together a service that replicates the functionality of redis", then that illustrates what would actually happen in the real world.

For example, for a very junior Python developer, writing something in C is basically like asking a C developer to write assembly- possible, but they'd have to learn a lot of different things to do it.

Similarly, when I write Java, I want to be calling Arrays.sort(myarray) instead of writing my own sort (if the focus is on developer convenience and development velocity).

So, it's just a difference in what you're desiring to measure.