I think Parris is being very simplistic. The problem is far more subtle and complex than this.
Whatever rules are made (he suggests that risk of death and death only should be the rule for admission) how do you prove their validity? We have to assume that anyone prepared to risk their lives by fleeing has some valid reason to fear.
Of course terrorists and others will hang onto the coat tails, but in principle we cannot send people away to oppression and misery. I do appreciate the logistics are hard, but we have to have some bottom line decency in operation.
We sacrificed thousands in two world wars in an attempt to establish decency and honour as basic principles - we cannot really abandon them now.