I don't see why the support rep can't give a clear answer. It was the same thing with Rockstar regarding properties. I like when people keep it clear and simple without playing around with words.
If it's not possible to buy residentials in Singleplayer, then it might be worth to make a petetition about it. I understand if there may be techniqal problems with the player having like 70 safehouses.
But in my opinion it should be possible to choose, pick from a great variety and then have at least two safehouses. For instance, it would make it possible to have one safehouse in Los Santos and then somewhere in the countryside.