To the extent we can draw any kind of realistic conclusions based on what we actually know---which ain't much---I agree with authentic. I remember when the word first came down that Gibbs was retiring, and fans went crazy assuming Snyder was somehow behind it. Then we found out Snyder all but begged Joe to stay.
Snyder and Swanson go way back, and there may well have been conversations over the past weeks/months about the possibility of it being in the team's best interests if Swanson retired, but I won't take it farther than that. My guess is Karl was done anyway, and with the sea changes in the organization going on top to bottom, he and Dan agreed it was the right time.
But it's all speculation based on the tiny fraction of the big picture we get to see.