No it won't come apart if it can't lock. The carrier actually will split in half from the axles locking up, if they don't lock up, it never sees that kind of load.
Any differential can fail, open or not, but it shouldn't split in half like they do when in operation.
Now, if this is a daily driver and thats all you are going to do with it, no beating on it, no spinning tires, stock tire size, etc., then the gov-lock is not *likely* to fail you. Power and big tires are what break them. Plenty of people (myself included) got a lot of mileage out of them with no issues.