Nothing seems really scary on the 71st attempt. If he knows the material very well and he believes that this material is going to be helpful to the audience, he shouldn't be scary. However, some practical tips from great speakers will boost his confidence, like: how long should a talk last, what is the structure of the talk, when to tell a joke and when not.
Personally, when I have to do something I've never done before, I usually try to be a perfectionist and then miserably fail the first attempt
That's why practice in front of friends, family, maybe a group slightly less than 300 people is vital.
I also like to take advices from the PRO's 'cause that boost my confidence like "I know what most of the people who will do the same thing with me don't know" - that always powerful.