For talking purposes, I've already gone to the simplest definition of "life" I know: self-organizing and self-reproducing, thus including viruses and prions.

The paper talked about bacteria, especially the lithophilic and thermophilic types most likely to be 'lucky' enough to be trapped in impact ejecta without cooking, and surviving the heat of entry into another atmosphere... with the benefit some bacteria have of going into 'spore mode' during the long, cold, gamma-ray strewn trip.

I doubt there's anything more complex that could survive the setup conditions for this hypothetical panspermia. I also doubt anything more complex than prokaryotes would have had time to evolve during the epoch under discussion, when interstellar distances were small enough for the journey to even be considered... so let that stand as the benchmark for "evolved life".

Fermi's Paradox deals with interstellar civilizations, stipulating a great deal more evolution... of which the first necessary characteristic is the ability to build an environment in which to survive otherwise hostile surroundings. Without that talent in the mix, we have no argument: interstellar travel by any life more evolved than bacteria is not possible -- and for bacteria, only for a certain few species, over limited times/distances.

But without that talent in the mix, added to the ability to send artificial environments out of the local gravity well, we're not talking about the Fermi Paradox.