It happens plenty already (informal criteria that a new hire must be a "diversity candidate" or somesuch), but if that's a strict requirement rather than an aspirational goal and if word gets out, you get hit by a Title VII lawsuit from someone who has good cause to think they'd have been hired if it weren't for their race / sex / sexual orientation.

So, if you're not sure whether it's a joke or not: it's a joke.

Has to be a joke.