Again, I don't think it is accurate to say that the Pelicans are sitting AD to tank. They haven't sat any of their other impact players and didn't firesale at the deadline. This is them reacting to a specific situation with a specific player that doesn't necessarily intersect with tanking.
Regardless of what their reasoning is, that's their problem. It's a risk they took by not trading him. So long as the NBA ties contract bonuses into performance via things like All NBA selections, a player in Davis' position absolutely has a right to have a grievance if his team tries to sit him when he's healthy and wants to play. And the league and the PA have an obligation to look out for him.