  Is the secondary component of GW190814 the lightest black hole or the
heaviest neutron star ever discovered in a double compact-object system [R.
Abbott et al., ApJ Lett., 896, L44 (2020)]? This is the central question
animating this letter. Covariant density functional theory provides a unique
framework to investigate both the properties of finite nuclei and neutron
stars, while enforcing causality at all densities. By tuning existing energy
density functionals we were able to: (a) account for a 2.6 Msun neutron star,
(b) satisfy the original constraint on the tidal deformability of a 1.4 Msun
neutron star, and (c) reproduce ground-state properties of finite nuclei. Yet,
for the class of models explored in this work, we find that the stiffening of
the equation of state required to support super-massive neutron stars is
inconsistent with either constraints obtained from energetic heavy-ion
collisions or from the low deformability of medium-mass stars. Thus, we
speculate that the maximum neutron star mass can not be significantly higher
than the existing observational limit and that the 2.6 Msun compact object is
likely to be the lightest black hole ever discovered.
