  We consider the stability problem for a unitary N+1 fermionic model, i.e., a
system of $N$ identical fermions interacting via zero-range interactions with a
different particle, in the case of infinite two-body scattering length. We
present a slightly more direct and simplified proof of a recent result obtained
in \cite{CDFMT}, where a sufficient stability condition is proved under a
suitable assumption on the mass ratio.
