The dishonesty isn't in the multiplayer not being there, nor the use of engine, the dishonesty is threefold:
The legality of this game is now in question. At first I and many others assumed, that, since it was using a custom engine, the legal issues would be diminished. But oh boy, were we wrong. Now, I have no issue with the engine being used-- but I don't want to be downloading Starcraft, a game I'll never play, just to play a fan made Bionicle game. Because it is using an engine that is tied to a specific game, many people will just see it as a mod to that game, and the legitimacy of Quest for Mata Nui will go down and down.
Therefore, because Crainy said that it was a custom engine, and in many respects it is, but it is still at the core the Starcraft engine. If I was making a similar game, say for Chima, and I made so many customizations and modifications to say, the Unity* engine, could I say that I'm using a custom engine I made by my own? No. It would still be a Unity-based game. This, to some, might be seen as dishonest behavior.
Not only did Crainy say that he was using a custom engine, he also said that multiplayer would be in the game, and advertised it as such. Now he takes it out, due to an "artistic choice". This too, could be seen as dishonest by some.
Now he says that the game is not a mod, just like a game in Unity is not a mod. He gives the reason that most of the game's assets, programming, and processing were done from scratch. Therefore, it is similar to Unity, according to his view point. However, the problem is, as I said, there is a difference between the point of the two engines. Starcraft's engine was specifically designed for use of Starcraft and customizations to it. They have allowed the use of it for custom games, but that is not its purpose.The Unity engine, however, is an all purpose engine for any game or simulation. It is not tied to one specific game-- rather many use it for a variety of purposes.
He says that the limited amount of assets shared between the two is likewise with buying assets from Unity. However, again, the assets of Starcraft were made for the game-- the assets for Unity are again, all purpose.
He again says he is justified in using Starcraft's engine, because it is modified to such an extreme that many aspects are not like Starcraft. But that does not negate the fact, some might point out, that it is still a mod, since it is based on Starcraft, you need Starcraft on your computer to even run the game, and that it has only been possible through Starcraft.
On a personal note, this has, in affect, changed my view of the game, but not in the same way as Faber and 3IONICLE. Faber, though mysterious at times, never was dishonest. As soon as April 1, rolled around, he explained that meetings were cancelled and plans had shifted. Disappointing? Yes. Dishonest? No. However, the team of Quest for Mata Nui made it seem as if it was its own thing. I guess it was so that people wouldn't think it was a mod, but that backfired.