The Packer critique is, essentially, that the film presents itself as revealing the truth about Snowden, but suppresses things that the filmmaker knows, but that she doesn't show us.
I am most interested not in how fully revelatory the film is about how and why Snowden made his disclosures, but in the disclosures themselves.
In a society based on citizen self-government, the citizens must know the facts (ALL the facts), or they can't properly provide the direction to their government that democracy demands.
According to Packer, Snowden began with a preoccupation about personal privacy, but ended up with efforts to destroy governmental secrecy.
No "privacy" rights for government, in other words.
That's what I think.