I figured it out, so I'm going to let everyone know for those that don't.

If you have a user who has priv level 3, then the commands that you want to hide need to be configured for a higher priv level.

Running a '?' at the # prompt came up with a slew of commands to run, but wouldn't because they weren't granted access. I wanted to hide these, and in order to do so I did:

Router(config)# priv exec level 5 telnet

That hides the telnet command for priv level 3.

HTH,

John