“Dr. Shostak argues that interstellar travel will always be so expensive that societies will always elect to explore deep space through some version of SETI—by communicating through radio transmission or other long-distance means with other civilizations.”

Pretty durable for a straw man.

Be frustrated no more. The prevailing assumption that aliens will eschew interstellar travel in favor of radio transmission due to the presumed cost of space travel went out of favor in the 70’s. It would be a case of using the logical fallacy of the strawman to assume that claim is used in general anymore.

I don’t think the eyes of advanced extraterrestrial civilizations will turn toward us until we learn to communicate the way they do.

Until then the best we can hope for is contact with aliens as backward as we are.

It “costs” fish to swim. Otherwise why would they bother eating and breathing?

I do think Tonnies has a point. Since the only thing we actually know about interstellar travel is that we don’t know how to do it, how can we estimate its cost for another civilization? And why would we assume it’s ever going to be resource-effective for a civilization to shout at random into infinity on the off-chance someone will accidentally hear it, and will then bother to exchange messages that will take years if not centuries to arrive?