I think it was a bit dismissive of your son to just say "Oh, okay." He could have just said thanks and that's it--not need to reiterate that he only wants to be a restaurant chef, etc.
Your son should know what a personal chef does! If he wants to be taken seriously as a chef at all, he should have as much information as possible about the different aspects of his profession.
More information is always better than less.
The thing that I taught my kids was that regardless of what they wanted to do, they needed to be flexible so that in a changing marketplace they could always support themselves and fulfill their dreams.
My youngest son went to LA to be an actor and model. He found a little bit of success but not enough to live on. Then, he served as a waiter a famous person and her SO and they invited him to come work for them on their personal side businesses. It is still the entertainment industry, just not working as a model and actor, altho he can still pursue that on the side.
He actually called me to complain about it once! "I want to be an actor mom, not a producer!"
That was about 6 months ago. Now, he is loving it. Loving the small but consistent paycheck that comes along with it which means he can keep living out there supporting himself. Loving that every day is a different adventure and he still gets to act and model from time to time.
It's not a big time job but it could be. It's the right place to be to learn and make connections.
The road to one's dreams will usually take a few twists and turns. It's never a good idea to completely rule out learning about tangent opportunities in one's chosen field because at some point, one or more may be an important stepping stone to what it is you really want to do.
Maybe the information that your husband got for your son is not the most important piece of information that will lead to his future, but your son learning to be open to it and other possibilities and being appreciative of someone close to him who obviously cares about his dreams is an attitude that could make a difference down the line.