What Mack was actually doing was “testing the people” to weed out obvious kooks and liars—so I guess that is a form of testing the evidence.
However, he was totally baffled by the folks he did believe.
When confronted with contradictory claims (”aliens are good” vs “aliens are bad” for example) he had no real basis to decide either way, and no real criteria to figure out how to decide.
To me the main message of all this is that homo sapiens need to lose the arrogance that “this culture has figured it out”.
We haven’t figured out squat imho.
We may have to survive a million years to get even close....easier said than done....
And, yes, Mack seems to have ended up in the aliens are not a threat camp.
I think he was wrong to some degree (depending, as you say, on which "alien" group we are dealing with).
As an aside, I think the government has already made its "disclosure." They don't know what "it" is but "it" is already here...and it isn't Russia, China, or us.
I think humanity is about to enter a new paradigm that has not been imagined and may not have been even capable of being imagined.