After reading this thread, I see nothing else beyond a he said/she said diatribe between NW and the passengers. There is no substantiated evidence on either side that affirms their version of the events. Substantiated evidene would be something like: FRA airport officials showing security footage demonstrating whether said passengers were at the appropriate check in, security, and gate areas at the required times.

Given the lack of real evidence, it seems NW has decided that the proper business decision is to issue an apology, offer some compensation, and protect itself in the media.

NW's apology is not a corroboration of the claims made by the passengers. It happens all the time, and despite what a few have claimed, there is no evidence that NW did anything inconsistent with its rules.