Wall glitch means using an explosive or molotov through the blocked area of the other player, from which he can't shoot, that's why it is disallowed because it is a clear disadvantage to the player who can't shoot through the blocked side.
Example: Near a wall or a closed door.
That guy was near you on an open ground not a blocked place and you were able to shoot him.
Hence the report is
denied.
I hope now things are clear for you,
@WhiskeyX