Can't imagine them doing that, but at the same time, shouldn't the Celtics focus be on trying to find the player who best solves their needs and can contribute to a Championship run. As opposed to trying to pick up some future assets.
They should maximize the TPE. Fournier is overpaid, but he's not a bad player, and while not perfect he is a scorer and ballhandler off the bench, a key need. If you get a 1st with him, you can then use your other TPE, your MLE and that pick to hunt other guys you want. The Celtics are unlikely to make only 1 move this offseason.
I do think they're better off with other TPE options, BUT... Fournier is one of the better players you could add in that TPE, and him coming WITH a pick instead of costing one opens up a lot of other opportunities (like say adding a C with the MLE or Juancho TPE, then using the pick, more picks and some salary (say Theis, Nesmith, etc.) to add another player.
Fournier wouldn't be the top of my list (especially since the pick stapled to him isn't going to be the Knicks' pick), but I'd rather have Fournier and a pick than say.... Jae Crowder. It's all a question of what players are available to fit the TPE and what you have to give up to get them.