Your argument has some logic behind it I think. Hood is slightly better in PnR and off the dribble this year. Fournier is a better spot up shooter, and has a higher assist %. I think Fournier plays to his strengths more than Rodney does, and his strengths would fit really well in this system more than Rodney's do. You could argue that Rodney is being asked to take tougher shots by the coaches and would be more efficient than Fournier in his role. But then you look at the spot up numbers and question whether or not more would help since rodney has much worse efficiency when spotting up. (1.23 PPP to 1.02 for Hood.)
The question is do you want a player that is a slightly better iso and PnR scorer (not great at either) or a player that is a much better spot up shooter and better distributor? You would have to believe that Hood is going to make another jump assuming they end up with a similar salary. On a team with Rubio, Mitchell, Exum (all slashing, setup guys to one degree or another) I think fournier is just a better fit than Hood unless Hood makes a Hayward-like leap. But taking role into account I can also understand why you might think Rodney would have a higher ceiling.
Anyway. I don't think your argument is ridiculous, but I think you would be betting too much on a player with a troubling injury history morphing in to a more effective iso and PnR scoring threat. Like I've said repeatedly I think Fournier fits in this offense like George Hill did. Or maybe more appropriately like Ingles with less of a conscience.