Leeway with 'virtually certain' ?

[salfordlad]

The player is responsible for knowing the Rules and for applying them to their own game. [1.2a] No other player has any authority over him; no other player can direct him as to what he must or mustn't do. If they do not agree with his action, all they can do is report the matter to the Committee. In stroke play, a marker can refuse to certify a score [3.3b(1)] which leads to Committee involvement. In match play, a player may request a ruling [20.1b]

If a player in your group is claiming KVC ball in PA when there is clearly a non-trivial likelihood it could be outside the PA, keep this Rule in mind:

20.1c Rules Issues in Stroke Play....

(2) Players Should Protect Other Players in the Competition. To protect the interests of all other players:

• If a player knows or believes that another player has breached or might have breached the Rules and that the other player does not recognize or is ignoring this, the player should tell the other player, the player’s marker, a referee or the Committee.
• This should be done promptly after the player becomes aware of the issue, and no later than before the other player returns their scorecard unless it is not possible to do so.

If the player fails to do so, the Committee may disqualify the player under Rule 1.2a if it decides that this was serious misconduct contrary to the spirit of the game.