I've been useing square for almost two years now and have never had a problem. I've done a couple of thousand of dollars a day in car transactions and never had a problem. Now the things you're friend is mentioning are in their terms of service.
So my advice is this. If you own or operate an actual business that pays taxes, keeps records, ect ect cool. What the above prevents is people portraying themselves as business when they truly aren't. So if your friend is a legit small business then he's golden, however if hes just "Joe Hobbiest" doing this on the side doesn't keep any records just breeds and sells snakes to make some extra money on the side and wants to use square to except credit cards he may be out of luck because that's not what they are designed for.4. Verification and Inspection
If your request to open a Square Account is approved, Square may request additional information from you at any time. Square may ask you to present invoices from your suppliers, a government issued identification such as a passport or driver’s license, or a business license. Square may also ask for permission to inspect your business location. If you refuse any of these requests, your Square Account may be suspended or terminated.