Stop calling Gi-Hun's plan stupid

This "take the soldiers' guns and infiltrate the control room" is his D or E plan at that point, all else failed.

First they tried to catch the Frontman himself in the Limo back in Seoul.
Then he had the dental implant tracker, which they removed.
He had the whole team of soldiers with the drone searching for the island.
Then he tried to stop the game by vote on multiple occasions.

All of these failed, so this may be why this half-baked plan is all he could come up with.
Plus he didn't take into account that one of his best soldiers (Player 001) would betray him right at the end.