Wanchai some people on here will be impressed by the views of a lawyer, you may not be admittedly. Kerr knows this and uses this to his advantage. Plus how many people would be confident enough to argue with a lawyer. Its what they do.
If I was to pretend to be somebody on here if it wasn't illegal to do so I would choose to tell everyone I was a Lawyer. Why? Highly qualified, respectable, hard to take on in an argument because that is the nature of their profession. If they were easy to argue down they would not be much cop as a lawyer. It carries weight. You are already one up on your arguee before you start the argument
Which also begs the question why does he have to tell everyone he is in the legal profession anyway. As you say who cares? There are very few people on here tell us what their professions are/ were. I certainly don't.
I would suspect one of the most highly qualified people on this board is mikemiller but you don't hear him saying what he does/ did to all and sundry to try to gain respectability. He argues from the point of view as being the same as anybody else hence his political views.