Rewriting things in rust is "cool". Bun did it, other projects did it. Therefore, writing a coding agent in one should be cool too.
And apparently enough HN crowd agrees with it to take the #1 spot on the board.
Having said that, I considered a Go/Rust rewrite of Dirac (https://github.com/dirac-run/dirac) for some modules to support cases when someone wants to run like 30 agents, but it quickly became obvious that, a) while the node event loop is a bottleneck, it is not the sole bottleneck and b) if you have a VSCode extension, you can't totally get rid of TypeScript, so it just becomes the case of bi-lingual project and the maintenance burden that comes with it
The author made the choice. Open sourced it (thanks!). So now we all enjoy more options. Saying author did so because "cool" does not sit well with me. It's feels like you get a no-strings attached gift of significant value and then going saying the giver gave it to be seen as cool.