The work was done at HRL, which Boeing owns a large part of (source: I worked at HRL).

Also, from my understanding, the most interesting thing about this material isn't the weight but the manufacturing process. To build the lattice they used a specialized 3D printer which combines the beams from a few directions, cf https://en.m.wikipedia.org/wiki/Metallic_microlattice

HRL is jointly owned by Boeing, Raytheon and General Motors. The parent companies commit to spending a certain amount on research every year, and researchers compete internally for those funds. This must have been a Boeing-funded project.

That unlikely ownership is an historical accident: those megacorps each acquired pieces of Hughes Aircraft, which built Hughes Research Labs, now HRL.