Since you are intent on taking this issue into personal domain, I respond.
In fact I was considering going to Tokyo and might still have gone had HND bookings not been pulled. I had been communicating with friends in Tokyo regarding my trip. The advice they gave me was to defer the trip, not because of radiation risks, but because of other practical matters, such as power outages, crowded trains as they are running on limited schedule, and because they would not be able to meet me.

1. I am not in the same position as DL crew.
2. I have no engagements in Tokyo right now. Had I an engagement, such as an interview or a scheduled meeting, I would go.
3. I am not scheduled to go to Tokyo. If I were, I would go.
4. I am not paid to travel to Tokyo.
5. My employer is not telling me to travel to Tokyo.

Primary function of airline employees, who work on the flights is to, well, fly. As long as DL, the employer has not cancelled the flights, they have few options except to convince their employer or quit.
This, I believe is not the forum to resolve a dispute between the airline and its employees.
I left Mississippi 6 months after the hurricane, as I was not able to function without a place to live, cook my meals, most restaurants were closed too, go to the bathroom, or take a shower. About a year and half later, my new employer suggested that I go to Mississippi to work on a project. I declined. I was offered twice my salary ( I was already making nearly three times what I had been in Mississippi). I still declined. There is always a choice, as long as one is willing to live with the consequences.