What if he never came back? Not everyone gets into jiu jitsu to be world champion. Some guys just jump in as a form of exercise and a form of self defence. Don't get me wrong, you need to keep it real with some people. Make sure they know they're only getting half the story, but ease them into it. "Look this will help you, but we're only drilling it and getting the movements, they're minimal resistance provided" Sometimes having a little knowledge is worse than having no knowledge at all.