I told you, there will be no airline (flying jets) that will allow you to work for nothing. When you come to find employment you enter a contract with that airline, a financial contract in which you work X number of hours for X pounds.
People who work for nothing indicate that they are not working for financial reward. These HR peeps will then attribute this to (a) this persons attitude to his flying is more akin to a hobby because he doesn't need paying and (b) if this guy is working for nothing what will his motivation and attitude be like when he needs to get up at 4am on a regular basis.
Not to mention possible strike action from the other pilots in the workforce who may find out.
End of story.