The ribs are certainly safe to eat. Though they might not have the tenderness you desire.
Tenderness and mouth feel is developed by the conversion of collagen to gelatin. This process happens slowly at low temperatures, but increases speed at higher temperatures. This is the reason why people more often cook things like ribs at 155F than at 130F.
The time you should cook your ribs also depends no small amount on what texture you want from them. It plays into what is the expected texture of a given item. In the case of steak people are inclined to expect a more toothy texture than they do with a roast or with brisket.