This is so embarrassingly idiotic and shows how Ford management (as well as anyone who does anything like this) is completely incompetent and unintelligent. Anybody is a guest when they are welcomed into anyone else's home or business. However, when you are there to be serviced in a potential business engagement you are BY DEFINITION a customer. So, basically Ford is just showing how utterly moronic they are by failing to use words properly in order to, in one of the most pathetic attempts at sophistry/marketing I can think of, cater to the lowest common denominator and the most sentimental. What a pathetic joke.
And the funny thing is that calling someone a 'guest' outright is usually done as a hostile reminder that they have overstepped their bounds and could be asked to leave or to behave themselves. Therefore, it is like Ford, in its embrace of stupidity is being unintentionally hostile and aggressive towards the CUSTOMER.