A couple of statements jumped out to me as suspect...
"Our conclusion then is that life is continually arriving to Earth from space, life is not restricted to this planet and it almost certainly did not originate here"
I think he meant "did not originate *exclusively* here" or "may not have originated here"
"If life does continue to arrive from space then we have to completely change our view of biology and evolution"
Why? I mean, it could explain the origin of life on this planet, but why would it change our view of evolution?