  We examine the metal-insulator transition in a half-filled Hubbard model of
electrons with random and all-to-all hopping and exchange, and an on-site
non-random repulsion, the Hubbard $U$. We argue that recent numerical results
of Cha et al. (arXiv:2002.07181) can be understood in terms of a deconfined
critical point between a disordered Fermi liquid and an insulating spin glass.
We find a deconfined critical point in a previously proposed large $M$ theory
which generalizes the SU(2) spin symmetry to SU($M$), and obtain exponents for
the electron and spin correlators which agree with those of Cha et al. We also
present a renormalization group analysis, and argue for the presence of an
additional metallic spin glass phase at half-filling and small $U$.
