On Sun, 3 Dec 2017 23:27:57 -0500, Mike_Duffy
wrote:
My point re-phrased should thus have had something to do with an
estimate
of the fraction of the known objects in the Solar System that have
perihelion less than 'Oomuamua.

It' s a small fraction but still a very large number. SOHO discovered
about a thousand sungrazing comets, some of which passed so close
that they
even collided with the Sun.

Nothing prevents an interstellar object to pass arbitrarily close to
the Sun. It's all a matter of probabilities. And even the improbable
does sometimes happen.