is SETI a scientific experiment? is it falsifiable? is the falsification simply a lack of alien messages? is it repeatable?
In the context of what it's trying to test, yes. SETI isn't trying to answer the question "is there intelligent life beyond your Earth?" It's trying to answer the question "can we detect intelligent signals from beyond the Earth?"
If it turns out we can't detect them, then we can't. That could either be because we're too stupid to do so, or because they aren't there to detect. Either answer need have nothing to do with the actual existence of extrasolar intelligence.