The customer is always right! How many times have you heard this adage? In all honesty, I would not want to work for a company that believes or works with this principal in mind.
Why would your employees have to bear the consequences of an angry impolite client? That client is a one-off instance while your employee is here for the long term. Invest in and protect your employees as they are the reason why you’re making money. Don’t let an employee feel that a contract (or for that matter a customer) is more valuable than them. There is nothing more devastating to an employee than to tell them that their time, efforts, and careers are less important than a paying client.