  Satellites of extrasolar planets, or exomoons, are on the frontier of
detectability using current technologies and theoretical constraints should be
considered in their search. In this Letter, we apply theoretical constraints of
orbital stability and tidal migration to the six candidate KOI systems proposed
by Fox & Wigert (2020) to identify whether these systems can potentially host
exomoons. The host planets orbit close to their respective stars and the
orbital stability extent of exomoons is limited to only $\sim$40% of the host
planet's Hill radius ($\sim$20 R$_{\rm p}$). Using plausible tidal parameters
from the solar system, we find that four out of six systems would either
tidally disrupt their exomoons or lose them to outward migration within the
system lifetimes. The remaining two systems (KOI 268.01 and KOI 1888.01) could
host exomoons that are within 25 R$_{\rm p}$ and less than $\sim$3% of the host
planet's mass. However, a recent independent transit timing analysis by Kipping
(2020) found that these systems fail rigorous statistical tests to validate
them as candidates. Overall, we find the presence of exomoons in these systems
that are large enough for TTV signatures to be unlikely given the combined
constraints of observational modeling, tidal migration, and orbital stability.
Software to reproduce our results is available in the GitHub repository:
Multiversario/satcand.
