is this actually true?

Well likely only "anything" that doesn't cut into the corporate goal of making a big profit hon. PetCo's not in the business of losing one single cent on anything they sell, most big chain pet stores put the bottom dollar well before good husbandry.

Can they be housed together? Sure. Should they? Nope.. I can think of a hundred reasons..
Ask them how they know the sexes of the snakes.. if not, ask them why it'd OK to put two adult animals together that could mate when they are too young.. sigh; stupid people abound. :(

If this "test" you have to pass reflects the things you are learning that they operate by it will be an interesting test...I would like to see it and their "answers" LOL. Keep in mind in order to "pass" you'll likely have to purposefully answer wrong or as they see it correct. I wouldn't put the time into it unless your looking to expose their wrong doing. Like others are saying you will likely have to operate within the corporate guidelines even if you are deemed a "specialist". Thinking you will go against their grain and try provide proper husbandry may not work out the way you hope.