You don't disregard them. As crew you still monitor them. But once past your EEP, and an ERA unexpectedly goes below landing minima, you may continue as planned (although company policy may suggest otherwise).
At the end of the day EDTO / ETOPS is all about statistics.
There is a measurable statistic about the chance of an engine failure when past the EEP. (looking at historic type data)
There is also a measurable statistic of weather at an ERA unexpectedly falling below the minima when it has a buffer on it. (historic weather data).
Multiply the two together and you have a vanishingly small number (risk) that is deemed acceptable for commercial operations.