  A binary neutron star (BNS) merger can lead to various outcomes, from
indefinitely stable neutron stars, through supramassive (SMNS) or hypermassive
(HMNS) neutron stars supported only temporarily against gravity, to black holes
formed promptly after the merger. Up-to-date constraints on the BNS total mass
and the neutron star equation of state suggest that a long-lived SMNS may form
in $\sim 0.45-0.9$ of BNS mergers. A maximally rotating SMNS needs to lose
$\sim 3-6\times 10^{52}$ erg of it's rotational energy before it collapses, on
a fraction of the spin-down timescale. A SMNS formation imprints on the
electromagnetic counterparts to the BNS merger. However, a comparison with
observations reveals tensions. First, the distribution of collapse times is too
wide and that of released energies too narrow (and the energy itself too large)
to explain the observed distributions of internal X-ray plateaus, invoked as
evidence for SMNS-powered energy injection. Secondly, the immense energy
injection into the blastwave should lead to extremely bright radio transients
which previous studies found to be inconsistent with deep radio observations of
short gamma-ray bursts. Furthermore, we show that upcoming all-sky radio
surveys will constrain the extracted energy distribution, independently of a
GRB jet formation. Our results can be self-consistently understood, provided
that most BNS merger remnants collapse shortly after formation (even if their
masses are low enough to allow for SMNS formation). This naturally occurs if
the remnant retains half or less of its initial energy by the time it enters
solid body rotation.
