One of the fish core devs here. You can ask me anything if you like. Happy to forward suggestions to the rest of the team. I've shared my opinions in the linked GitHub thread under the @mqudsi handle.
One of the common refrains is that the Rust community pushes people into doing these sorts of things. How many “you should rewrite it in Rust?!?!!” messages have you all received in the years? If you got any, how did they weigh in on this decision?
The enthusiasm of the person asking the question was evident.
What was trickier to handle was their insistence that "X would be better if written in Rust" without really understanding what makes X successful.
This was further compounded a bunch of copycat projects written in Rust with very limited functionality. Their project's marketing said that "it's written in Rust!" was their primary advantage.
Fundamentally, users don't care, or even know, which language your software is written in. All they care about is whether your software solves their problem.
To answer your direct question: I got multiple "you should use Rust!" comments. I smiled, said thank you I know that Rust is the right choice for certain problems. I then asked "How would Rust help here?" and listened.
When Rust is the right language for the problem, I'll re-write. Until then, I'll be polite and listen.