When are the Devils likely to be true contenders? Next year? The year after? 2 years after?
If Palat falls off a cliff when the Devils are actually serious about winning a Cup, the contract will be a failure. Because they could use the cap space more efficiently or on a better player.
If the Devils were actually a contender right now, I wouldn't have much of a problem with the contract. Sometimes to win now, you have to pay the piper later. But that clearly isn't the direction Fitz views the Devils as in next season.
Heinen is a solid player. Did I say he was better than Palat? No. But giving him a cheap contract preserves cap flexibility and if he is displaced by the younger players, there are basically no cap consequences.
Smart teams are always managing their club with the long-term salary cap in mind. To reduce your analysis to "good player now, good deal" is actually absurd.