The actions of Volkswagen related to their diesel car admissions has violated the public trust. It is vital for any company to maintain the trust of the public to continue as a profitable entity. If Volkswagen stopped selling diesel cars in the US they would send a message that the Company understands that their breach of the public trust was unacceptable. That action, along, may move them back on the path toward regaining the public's trust in their other products.
Volkswagen was caught cheating emissions test in the United States a few years ago. They temporarily halted the sell of the cars involved in an associated recall. In an effort to focus on electric vehicles and improving green technology, the company announced it will cease selling diesel cars in the U.S. market. This is good for cunsumers and the climate.
After Volkswagen was caught manipulating emission tests to evade United States legal restrictions, they have been forced to pay penalties and buy back some VW cars from consumers. It will be impossible for people to trust them to fix the problem and sell diesel cars in the US market, so they should cease selling them here.
Diesel is good for some things and vehicles just like unleaded is good for others. People should have a choice in what they want to buy. Environmental warnings might be a more appropriate resolution to the controversy, rather than banning something outright. People in a free country should be allowed to decide what they want to do.