I don't disagree (no front brake on a bike is down right stupid) ...
But buyer beware. Many of use have bought bikes with faulty front brakes due to age and neglect. My PO certainly didn't divulge the info that my front brake was going to lock up on me on my first couple rides. This being my first bike I had no idea what I was in for. At least these people had the benefit of seeing that there was no rotor/caliper/master cylinder....
That being said. Selling an item as a dealer/refurbisher does come with some responsibility. My opinion is he DIDN'T hide anything, which is MUCH more than I can say for C.L. and Ebay sellers.
Once again, take what you read here as advice. Advice can save you, put you behind bars, or worse get you killed. And that's why it's advice and not something more.
As a part of my job I go with my boss to purchase cars for our fleet of limousines and sedans. I have heard every lie in the book. In the end the purchaser has all the leverage. If you want the truth and dont know the answer take it to a professional. If the seller won't let you, he's hiding something or not worth dealing with. PERIOD.