Is it ok to mock somone because of their accent?

Congress of the People MP Willie Madisha mocked ANC MP Naledi Pandor's English accent in Parliament. Was he out of line? Is this acceptable behaviour?

Making fun of a persons accent is dangerous. Your accent is used as marker for your race, class, education level, and in South Africa is has been a source of enormous hurt in the past. 

Is it ok to mock someone because they do no speak the way you do?