We are nowhere near advanced enough to say that life, complex or intelligent, doesn’t exist anywhere near us. There is no reason to believe an intelligent spacefaring race would make themselves so obviously detectable that us stupid primates could see them. And for non-intelligent life, we’ve been able to confirm mere thousands of planets. We have a very long way to go before we can start talking about the meaningfulness of a lack of life signatures in the atmosphere.
The user always lies. Or even if they don’t, they can’t intimidate the ghosts in the machine like you can.