I read that Lombardis contract isn't insured, so if he doesn't play this year, the Preds would be on the hook for the value of the salary. Since they are a team that works on an internal budget I can see why they would be wary to have that much money in the press box.
From the Leafs standpoint, if he plays, great. They have 3 skilled centers. If he doesn't, oh well. They get a good young defenceman in Franson and they are not as concerned with actual dollar value.
As mentioned above, the extra 3 - 4 million can now be used by the Preds to sign Weber or Rinne longterm, so if they manage that it is a win for the Preds.