That was in the rules and quickly abandoned. What they care about is that you don't load new code from the Internet. Ostensibly, the reason is security, but the real reason is they don't want you to make an app store.

JavaScript in webviews is excepted because you couldn't show a website without that.

If you don't get new code from the Internet (for example, someone types it in) that's ok. It's even ok to copy and paste it from the Internet.