Check out the original RFC to find the genesis of this effort. Here’s the opening pitch:

We know there are huge costs and risks in introducing a new main language in the kernel. We risk dividing efforts and we increase the knowledge required to contribute to some parts of the kernel.

Most importantly, any new language introduced means any module written in that language will be way harder to replace later on if the support for the new language gets dropped.

Nevertheless, we believe that, even today, the advantages of using Rust outweighs the cost. We will explain why in the following sections.

Godspeed to everyone collaborating on what will surely be a massive, years-long undertaking.