I will concede that perhaps for the next 2-4 years things may be difficult for them at a major. But the history shows that unless a person is an actual, honest to goodness, name on the "Jumpseat Protect List", scab, all will eventually be forgotten or forgiven. Even then there is a chance you could officially be forgiven as ALPA officially forgave the Continental scabs when ALPA realized they had a realistic chance of getting their money. Back in the early 2000s the internet message boards were alive with the rhetoric that the Freedom Air guys would end up on a list and never be able to get another job. Now barely anyone remembers what Freedom Air was, let alone remember that the guys were not supposed to get hired. Around 2005/2006, GoJet guys were the new bad guys, and the internet message boards were alive with the rhetoric that those guys will never get hired. Now, 13-14 years later, nobody cares whether someone was at GoJet.
Unless there is an economic downturn, or a 9/11 type catastrophic event, within then next 2-4 years most people will have forgotten about Norwegian and have moved on, and these guys will not have issues getting hired at majors/legacies.