No it says that it will show you the script first so you can review it. What I don't get is why do you nee d a program for this, you can simple curl the script to a file, `cat` it, and review it.

It shows you the installation script but that doesn't help you evaluate if the binary that the script installs is itself safe to run.

Yes but even if you inspect the code of the installation script the program you just installed might still be compromised/malicious? It doesn't seem more likely that an attacker managed to compromise an installation script, than that they managed to compromise the released binary itself.