But at the same time if your kid isn't believing in Santa then he's going to have to carry that opinion around and interact with other kids that do believe in S

But at the same time if your kid isn't believing in Santa then he's going to have to carry that opinion around and interact with other kids that do believe in Santa. This will help them ponder "truth and lies" in the same fashion. Saying "doing something technically wrong to my kid cause it improves them" isn't a terrific argument IMO.