Just like the Witten restructure you yourself pointed to. They did what they needed to do for Cassel and his contract. They very easily could have done the exact same thing months earlier for Fitzpatrick had they chosen to. But you go ahead and keep trying to sell a capped out team story that nobody's buying for a second.
That is what you are missing - or purposefully ignoring. There was no easy restructure to pull money from or it would have been done much earlier to have more FA money in the first place. Witten was the contingency plan because you always have to have backup plans to deal with injuries (like that one).
You can't waive a magic wand, as much as you want to. You can create the room, but its at the cost of some bad options like freeing up 2 MM by guaranteeing Brandon Carr another 5 Million for another season. There were no easy options at that point.
Its a simple question and if there were a lot of simple answers like you claim, you could have pointed to one right away.