If I were Apple, I would develop the tool to retrieve the data. But I would NOT give the government the tool. Period. If the government wants the data, hand the phone to Apple, let Apple unlock and retrieve the data, then let Apple insure their tool is not handed to the government.
The only legal reason that Apple has to fight this order is that the tools don't exist, and creating them would be an undue burden under the Act (demanding that they create something that doesn't exist in order to help the government). What you are proposing would forfeit the case instantly.
If I were Apple, I would develop the tool to retrieve the data.
Lynch is too cute by half when claiming that their request is to just unlock this one phone. That one time sets a precedent large enuf to drive a 18 wheeler truck through.
I agree with Apple that Congress should make this call, not an unelected judge.