Are you sure you're replying to the correct comment?
Sorry, you're right :-) I meant to comment further up where people asked if we could reference rustup.rs in the installation instructions.
Actually, there is already an issue for this: https://github.com/google/comprehensive-rust/issues/19 and I hope someone will fix it soon :-)
I'll be happy to update it to suggest using rustup like "normal". Could you make a PR for that?