An interactive shell (like bash/python/irb) is untrusted code (i.e the user can type whatever the hell they like). But I don't/shouldn't need root to run it.
His point was that you need root "to install it", not "to run it".
Wait, but 'install' means 'download' ? So if chrome was a single .py file, which I downloaded, and ran with python. Thats fine. But because it's a .exe, i need root... ?