It seems to me that as soon as he entered this world as "Kamin" he would try to do something about it. Even if the Kataans didn't know how to build a subspace transceiver, he likely would have known how to. This is due to the steep technical requirements associated with being a Star Fleet Officer. Successfully building one would have probably demonstrated to him that things were not right in the universe.
Even five years into the simulation he is still exhibiting his superior technical knowledge:
He suggests to the visiting administrator that atmospheric condensers are needed to survive the extended drought they are currently experiencing. His ideas are rejected... (memory-alpha)
And yet despite the counsel's refusal to save themselves, Picard decides to believe the simulation rather than question it.
He builds a laboratory, he develops an advanced sunscreen, and yet no one is willing to use the things he wants them to. He should have been able to see that all was not as it should be in the world.