If the controller thought they were having an emergency (which I guess he did based on the strange approach and all the warning sounds he heard on the radios) it's not that uncommon to hold on to them. Happens because it reduces crew workload if he's not telling them a new frequency.

Tower and approach have a button to talk directly in each other's headsets, so it's easy for approach to give you a landing clearance on behalf of the tower. Or the other way around, tower could get you radar instructions from approach in case you have a problem right after take off and want to return immediately.

But in this case it was a very bad decision to do that.