It was a choice between him and Morgan, hindsight = 20/20.
No, it wasn't. Both Morgan and Witherspoon were made similar offers, and Morgan accepted his. However, even after re-signing Morgan, the Panthers kept the offer to Witherspoon on the table. In fact, they even increased it a bit when other teams showed interest. But then the Rams swooped in and offered him a ridiculous contract that exceeded the maximum value the team placed on him.
Point is, that revisionist history likes to say that it was an either/or situation, but that was not the case at all. The team wanted both players and were willing to pay for them...within reason.