Part of the problem is that he is in a big city. Cities have residential and business zoning. The folks who pay for houses have the right to peaceful existence. That is why manufacturing and most business is not allowed in residential areas. In smaller towns, this is not a problem. In cities you often have to either move the shop to a business zone, or work at home with city approval. The easiest way to legally do this is to get a PO box, have a quiet and enclosed shop, and apply for a work at home business license. You clearly state that you are making knives as a part time business, more like a hobby, and that you are selling them via the internet and at knife shows. State that no customers will come to or do business at your home. All business mail should go through the PO box. This is the usual set-up for most larger cities.
Lying, filing a misleading application, or operating without a business license, is just plain wrong and dumb. If you are an honest knifemaker, who stands by his product, be an honest businessman who obeys the laws and rules. There are many other requirements dealing with fire codes and noise codes that will need to be addressed.
Forming an LLC is one way to organize your business,but it has nothing to do with where you can run it. I don't know of any incorporated town or city that does not require a business license for an LLC ( or any other business) to operate. They are two entirely different things.
The best way to deal with business licensing for small at home businesses is to go in person. Take some photos of your work, and give realistic estimates of how little manufacturing will actually be done. ( I work an hour or two in the evenings and on Saturdays. I make about one knife a week.Etc.) This will put to rest the worry that you will be running a knife factory in a residential zone.
Finally, don't get an attitude with the person on the other end of the phone. He is your friend if you make him one. He is your worst enemy if you make him that,too. Be polite and when there is a question about what you need to do, or can and cannot do, ask him/her what you need to do to make it work. They are usually quite willing to help any small business get started.
Finally, if you hit a wall, ask your local councilman/woman for help and advise. You may have to apply to the city council for a variance.
Good luck and keep a positive attitude.
Stacy