Is that top or bottom skin? The bottom skin tab/fold nests inside the top skin tab/fold, so if it's the bottom skin, you may be able to get away with it as is. If it's the top skin, you'll kinda have to decide what's acceptable - I doubt this would fail an airworthiness inspection, though I'm in no way qualified to make that call.
For different reasons, I redid my trim tab recently, and it's one of the cheaper fixes to do, in all the categories: time, parts and shipping.
The "make a rib to close it out" is also an interesting idea.