"What does NOT RECOMMENDED mean....?"

When I see this statement, my instinctive reaction is: It's probably fine, unless you're a moron.

Remember, manufactures have to protect themselves from anyone that purchases the product.

I can easily see a manufacturer, and its lawyers, concluding that it's not a good idea to build a hot rod/performance car without the words "not recommend" when it comes to towing because of how Joe Q public might tow with it.

If there was a "real" problem with towing with it, they would use language different than "not recommended".