Since his case is difficult, I don't think he had to die, but because he was part of the government's rules on who has to die via punishment and the death penalty, maybe he should have known what he had gotten into. It is not always right, but the death penalty has strange good.
The IRA and its members want one thing. Independence. They want their own state, just as Scotland does. Bobby Sands starved himself for his cause. This was not the only way that he protested, just the last one. He had the option to eat. However, he refused to in protest. Was he right to starve himself to death? He sure believed he was. He knew the consequences and took that risk.
The prison officials should have looked into meeting some or all of his demands in a timely manner and should have ensured that he would not die from starvation. In my opinion, he died for a cause that was important to him but was not something that "was worth" starving yourself to death over.
Bobby Sands died as the result of a hunger strike he started in prison to try to get more freedoms in prison. The hunger strike centered on five demands: the right not to wear a prison uniform; the right not to do prison work; the right of free association with other prisoners, and to organize educational and recreational pursuits; the right to one visit, one letter and one parcel per week;and full restoration of remission lost through the protest. (Wikipedia) Frankly, I feel as though his death wasn't justified. Some of the demands he made were not appropriate for the setting and they should not have been met and they were not. He didn't eat for 66 days, he could have simply started eating again.
No, I do not think that the death of Bobby Sands was justified, because he died on a hunger strike. If a person is dead, they are not around to carry on a political message. Being a martyr might generate attention for a day, but after that, the message is lost. Sands should have found a different way to get the message across.