Did you read the article? The South Koreans couldn't decipher the content due to the extent of the damage and sent the black box over to the US. Do you think they colluded? Please take off your tinfoil hat on the way out.
I’m not asserting collusion, but they easily could have sabotaged it before sending it to the US. If the US finds sabotage on the recorder, it becomes a political decision whether to release this information against an ally.
This is well within the realm of realpolitik international political brinksmanship, no tin foil hat required.