Wow, on the Vikings swiping Johnson. Good move by them!
Ultimately the calculus of the FO was mistaken if you apply the retrospective approach to this situation. At present I'm unsure as to true cap hit the team will take but at best it is at least a million $ for the one game he played in recording 1 tackle. OTC.com says it is $1,027,390 dead money.
All in all the situation is one where at least an explanation might be needed for the owner as the team which is up against the cap has burned between $1+ million of cap on a roster move they might have avoided if Johnson had been cut prior to the 1st game.
Thanks Jville, updated on Coleman.