It walks you through installing a "cask" using "brew". It doesn't mention how to install homebrew but instead directs you to the homebrew homepage which shows the output of a curl command being fed to `bash -c`. Something that's both bad practice and unintelligible unless you're quite familiar with Unix shells. If everything works as intended, you're good to go! But if anything goes wrong, or you have to update the "cask" in the future you're left with little to no context about what you just did.
For someone unfamiliar with Unix shell commands, homebrew, curl, etc. this is a quagmire that can take days to unravel without someone there to help them.
You have to trust the place where you're downloading it from, of course. But there's nothing inherently worse about /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/inst...)" than burning https://cdimage.debian.org/debian-cd/current/amd64/iso-cd/de... and booting it up.
Or are you saying that you audit the bits of the ISO yourself before burning it?
https://docs.github.com/en/get-started/quickstart/set-up-git https://www.atlassian.com/git/tutorials
This one's always fun: https://learngitbranching.js.org/ https://www.tutorialspoint.com/git/index.htm