You could make a case that it is unsporting conduct... the criteria for it are rather vague so its basically a discretionary call.
now....
the opposing players could gently try to push their way through with a very slow but fair "charge" (shoulder to shoulder)... and they could still be within "playing distance" of the ball. They can use contact as long as the force is not excessive (or reckless/careless). Basically they can try to walk between the players to get at the ball, but I guess those players could respond with equal (non excessive) force in standing there firmly... which brings us back to square 1.
If it happened a lot in major international / FIFA games, they would make some new rule to deal with it...
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