Fly,
There are several loopholes options market makers can use to avoid delivery of the stock. For example, if they are notified of a buy-in, they offer out the stock (since they don't have to locate, they can offer it naked) and essentially buy their entire position from themselves. This doesn't change anything, but it resets the clock for reg SHO purposes.
Obviously, this kind of loophole contributes to persistent FTD problems and is easy to close without taking away the market makers' naked short selling ability. It just makes naked short selling more risky for them since they will have to deliver.
In fact, if the purpose of more short sale rules is to curb market manipulation rather than price controls, then enforcing delivery is the way to go. Price tests and pre-borrowing are expensive and suck liquidity out of the market. But a market manipulator will have to have massive kahunas to naked short if the risk of buy-in grows with every naked short sale. To increase this risk, the SEC need only enforce its own delivery rules.
The SEC's little games of late clearly have nothing to do with trying to curb market manipulation - it's all about price controls because people freak out when prices go down - unless it's oil, then they freak out when it goes up. Notice there's no talk of shorting curbs in the oil futures market? It's very likely they're selling phantom barrels. Why no outrage?