Was there something wrong with how they are currently written or do they just want the badge that says they converted to Rust?
License. GNU is copyleft and the new thing is permissive.
We might see a fracture open slowly. For me, even AGPL is not enough
Neither. They basically see Rust as the future. They want to be able to attract young contributors and to hire young employees who are excited about Rust and who want the safety features. Bear in mind, the average age of the Linux developer is increasing. They also see technical benefits in Rust. And they are increasing test coverage of both the Rust tools and the tools written in C, IIRC.
My source is this interview with the VP of Engineering at Canonical on this topic: https://corrode.dev/podcast/s05e05-canonical/