This article basically states that the chance of there being intelligent life outside of Earth is > 0% so obviously the chance of aliens is 100%. It doesn't provide any proof so the title is technically misleading.
What he actually said was "a probability for civilizations to form of one in 10 billion per planet was considered highly pessimistic [but] even if you grant that level of pessimism, a trillion civilizations still would have appeared over the course of cosmic history."
In other words, even if the paper's calculations are off by a factor of a billion, there must've been 1000 civilizations before us. And, no, that's not proof but more of a rethinking of a thought experiment based on new data.
If you wanted to dispute this, you'd have to show how any of the estimated numbers is wildly off or that the model (Drake's equation) is all wrong somehow.
