LogFAQs > #885205012

actual line from the creator on after the episode:

We were thinking, "How can you possibly survive that situation?" and we came upon the idea that the one way they could survive was that they would be in the middle of an island. And we thought if you put five, ten thousand wights on the ice, that might believably break it.

so yeah. essentially, they're not hiding the fact that they are moving the characters according to the plot and not according to the rules.
---

yet all sailors of all sorts are more or less capricious and unreliable - they live in the varying outer weather, and they inhale its fickleness