The Manhattan Project resulted in a product. That product changed geopolitics. The discovery of alien life wouldn't produce a product and would not change geopolitics (unless those flying saucers really do exist and are nearby).
Nobody asserts that the discovery of alien life would produce a product. Instead, pundits carry on about “the implications for our understanding of our place in the universe” or some other such rot. That's the focus of commentary on alien life and that's what I critiqued in that essay.
A) It didn't change the scientific paradigm. It was an extension of generally agreed on principles.
B) It didn't effect the day to day work of the majority of scientists.
That seems to be the criteria you are using, and they seem pretty strange to me in this case.