I don't think it follows that he would have to be aware of the Inquisitors. They didn't exist when he went in to hiding, and Tatooine is a backwater that isn't really under Imperial control at this point. Even if the Inquisitors were common knowledge, which they most likely aren't, its doubtful much if any information about them would reach Tatooine.chase128 said:
Surely he has to be aware of Inquisitors hunting Jedi and he should be prepared to handle them if they discover Luke. They do target Force sensitive children.
In the show we see Kenobi struggle to "reactivate" the Force. He could barely stop Leia from falling to her death.
Staying hidden would be a more effective survival strategy than preparing for the worst.