For the record: this exercise has taught me how diabolically clever some of our laws are from the point of view of creating situations where we as a nation are held hostage by our amnesty policy.

There's nothing especially clever about these particular laws. Sometimes Congress clearly and specifically says what the law is; and sometimes they leave it vague or give the Executive a lot of discretionary power. This is one of the laws where Congress has just pretty specifically said what the law is.

Again, that's probably just a result of when the law was drafted. In early 1980, the amnesty population was overwhelmingly fleeing Vietnam and Cambodia. Given our involvement in the wars there, our government's official policy towards the new governments there ("They're evil and Communist and they're terrible!"), and the fact that they genuinely were evil (the horrors of Pol Pot and the Khmer Rouge) made for an asylum population that had a lot of sympathy among the American public across the political spectrum.

This was a very clear moral question (of course people who are fleeing persecution should be able to take refuge here - we're not going to redo the MS St. Louis), and so the law provides very clear direction. It would be an ahistorical mistake to project present policy debates back forty years into the past.