But U-235 doesn't stop being U-235 because you pressurized or heated it up. Can't blow up atoms.
Best case, instead of a pile of enriched uranium, you now have a highly concentrated mine.
Sure, you'd have to separate it again, but getting U-235 away from dirt and rock is a lot easier than separating it from other uranium isotopes.
Even if it was stored as volatile UF6, what, you've converted it to UO2F2 / U3O8?
The expertise and equipment to develop and maintain a nuclear arsenal at scale is vastly more important.
But U-235 doesn't stop being U-235 because you pressurized or heated it up. Can't blow up atoms.
Best case, instead of a pile of enriched uranium, you now have a highly concentrated mine.
Sure, you'd have to separate it again, but getting U-235 away from dirt and rock is a lot easier than separating it from other uranium isotopes.
Even if it was stored as volatile UF6, what, you've converted it to UO2F2 / U3O8?