If Owen was connected to Obi-Wan and knew exactly the sort of risks Obi-Wan was taking not only with the child but with Owen and Beru's life, Owen wouldn't have to actually be Anakin's brother or met him for Owen to have the same reactions to Luke's questions in ANH.

He knows the story and his resentment towards a brother getting involved and making things dangerous for the folks back home could be a projection of his relationship with Obi-Wan.

The ROTJ novelisation backstory makes sense (sure the Star Wars (1977) backstory makes sense too but in a saga spanning context it's much more convincing than AOTC).

Let's face it, the farm, Owen and Beru were only in the AOTC to justify flashing the familiar at the fanbase.

They say hardly do or say anything and we get none of the dots connected to the OT.

Their only narrative purpose is so Obi-Wan can drop the boy off at their place in the final frame which in the context of how he does it doesn't make sense.

It would make more sense to have Obi-Wan pressure someone he knows and can trust into moving to a planet in the middle of nowhere and keep their head down even if they hate him for it.