Gordon D. Pusch wrote:

1.) Galileo's impact velocity will be so high it will wiff to plasma.
It is highly unlikely anything living would survive the process ---
or even the very molecules it was formerly made of.

Bacteria resist to incredible high accelerations (some were tested to
survive 1e5G) and pressure, such that shocked rocks accelerated to
escape velocities due to big meteorite impacts can be considered
as bacteria transporters to other planets.

Of course sufficiently high temperatures decompose any
material. But it is far from obvious that a complex structure
such as Galileo must be fully raised to high temperature.
After all meteorites do reach the ground keeping cold core although
entering the atmosphere with similar speeds as Galileo. Some
components of Galileo (presumably the one with plutonium) must be
built to resist terrestrial atmosphere re-entry.

2.) Jupiter's environment is most likely too alien for anything that
evolved on Earth to survive there --- even in the "water zone."

It would be safer here to say that today we don't know the limits of
adaptability of life. Already on Earth different life forms proved
to survive well in exotic conditions not expected by life experts.

3.) Jupiter has almost certainly already been hit by terrestrial material
ejected by asteroid impacts, just as Earth has been hit by Mars rocks;
hence, if terrestrial microorganisms _can_ survive on Jupiter, they are
probably already there.

This is the good scientific argument to use, but of course then the
whole dramatic crash justification appears as a lie to the public.

Note that all of the above are likewise true of an impact on Europa,
so this whole self-immolation maneuver is almost certainly pointless ---
it is basically just a misguided PR exercise to demonstrate JPL's
"environmental responsibility" to people who are still going to hate
and oppose them as a knee-jerk reflex response, no matter _what_ JPL does.