What I can say is that the Defensive license comes from folks who deal with M&A, noncompetes, and resulting complexities all the time. 1.0.0 has a number of provisions addressed to potential operational and structural changes that could affect scope:
https://polyformproject.org/licenses/defensive-licenses/1.0....
https://polyformproject.org/licenses/defensive-licenses/1.0....
https://polyformproject.org/licenses/defensive-licenses/1.0....
My own personal view is that the 1.0.0 terms will be perfectly well recommendable for a great many companies and use cases starting today. But also, emphatically, that any set of terms can be improved, especially in how they interact with external sources of complexity, like the corporate laws. I hope we'll see 1.0.1s and 1.3.0s and 2.0.0s and beyond for all the PolyForm licenses.
If anyone is or has the gas to contribute to those conversations, please reach out: https://polyformproject.org/contribute/
Let's say a database gets licensed under the defensive license by $CORPORATION_0. And let's say that $CORPORATION_1 makes many contributions to that database under the same defensive license (where they retain copyright). A little weird, but presumably both companies are comfortable with the situation.
Let's then say that $MEGA_EVIL_DB_CORP buys out the contributor $CORPORATION_1, and now $MEGA_EVIL_DB_CORP owns the copyright and has competing databases.
I'd assume both companies can no longer use the defensive licensed DB. Meaning all Oracle has to do to destroy the competition is buy whichever company is cheaper.
That seems like a bad attack vector.