"weapons-grade plutonium"
From the linked report:
In particular, the laboratory determined that the isotope composition of the plutonium found in the Nuclear Samples is weapons-grade, meaning that the plutonium, if produced in sufficient quantities, would be suitable for use in a nuclear weapon.
That sounds like a far cry from material ready for a primary, it could just as easily be a barrel of spent reactor fuel. All 'weapons-grade' means in this context is Pu-239, as opposed to other isotopes and reprocessing is job and a half. It would be interesting to know if it also contained Pu-240 but I have my doubts they'll release this information.