The main reason this was posted by NFL twitter was to show that the Green Bay Packers just picked up a huge piece to their previous defense.
It was creative in the fact they took a picture of Jaylon Smith on the Dallas Cowboys and put him next to a Green Bay Packers logo.
This post helps drive attraction to the two people who reported that signing.
The reason NFL picked Ian Rapoport and Tom Pelissero is because they were the first two to report the signing on Facebook.
https://www.facebook.com/profile.php?id=100073229873885