This checkpoint was unmanned when we cycled through. The gate was locked, but the fence towards the river had an open section for bikes to pass through. If manned, you may have to pay a fee to enter, but this is pure speculation. We encountered no checkpoint on our way to Daroot-Korgon, meaning that if you come from the south, you wouldn't have to enter anything...
Therefore, I wouldn't take this checkpoint too seriously. Feedback from your experience is appreciated though!