They can definitely test it. It's just that this test isn't quite to the significance level for most people to regard it is proof (although it's strongly suggestive). And if it's true - then it would suggest life is pretty common in the universe.
Imagine that being confirmed in our lifetime. Magical.
I can understand why people who are 15/20 years older than me balk at the thought of socialism. Just because of it being tied in with the cold war an the excesses of communism.
But because something didn't work perfectly 50 years ago - doesn't mean that elements of it woundn't work well in 2025.
Im not going down the 'all private property is theft' route - but paying a bit more tax for good quality public services that are under the custodianship of the state seems eminently sensible to me. Anyway - an argument for another day perhaps?