First of all 
- do not understand what he is doing
- do not understand that online activities like building sites, IT stuff can bring money
- do not understand that writing books, self publishing can bring good steady money long term
It is a problem of his parents being ignorant of today's possibilities/opportunities that did not exist when they were young. They are worried their son is wasting his youth/time/days on activities that he may be indulging in for pleasure without good prospects for work/income
About your example, when his parents go to a restaurant and have to deal with, communicate with, chat with a waiter at a restaurant, of course they are not going to treat that waiter bad. Why on Earth would they do that? Why would they treat bad people they don't know... It would make no sense and they would get kicked out to start with.
The thing is that the waiter at the restaurant is not their son, they are just making conversation and trying to have a good meal in peace. Only someone crazy would go around treating other people bad. Based on what parameters would they even think it would be ok to treat the waiter bad, it really makes no sense.
Reality is that his parents do not care about the stranger, they do not care enough about the stranger to feel the need to criticise the stranger.
Their son is their flesh and blood and they want the best for him. In their ignorance they do not understand that their son is actually trying hard to do something productive.
They do not know how to deal with the situation and see the late mornings in bed as being lazy or they may think he is at the computer up to 5am to play videogames for what they know...
There is no hypocrisy from his parents. Chances are that they act like that because they are genuinely worried about their son future, the do not understand what he is up to, they do not know what to do... so they end up stressed, frustrated, make mistakes...
RE: Battles for Psychological Independence in the Living Area