We should agree on a definition of "justified" if we want to have a productive conversation on the topic (and it's not THAT easy).
And are you referring to the particular situation of each SS member or the action of suicide from an ethical/philosophical point of view?
Let me elaborate on that. "Justice" is a human concept, or, better yet, an emotion/mix of emotions.
Like love, happiness, beauty, sadness, hunger, meaning, justice exists only in our brain/bodies.
You can't find any of those outside yourself and other conscious beings.
That doesn't absolutely mean that it's not "real" or it's pointless, just that no action is justified in-itself, we perceive it is.
The same as nothing is beautiful in-itself, we perceive it as such.
So what do we know about justice? Our personal experience/thinking and our culture/society shapes our sense of justice. It follows that it's not the same for everyone.
We can make countless examples for this claim, for one we don't feel that death penalty is a just punishment for blasphemy... in Saudi Arabia they do.
It's useless to try to think what is objectively justified, in the same way that it's useless to think what is objectively beautiful.
I think we can consider our personal sense of justice like a mix of emotions, wich is a good first step to analyze it globally, in THE MOST objective way possible.
1)Anger.
"All child rapists should be killed".
2)Envy.
"I worked harder than him but he got paid more, that's unfair".
3)Feeling entitled to freedom/rights.
"Stop telling me what to think and fuck off."
4)Empathy.
"My dog is in so much pain and I've decided to put it down because even if I'll miss him keeping him around to suffer is wrong".
Speaking from a personal point of view I feel that killing myself is a justified action and that keeping someone else from killing him/herself is not justified since it violates individual freedom w/o any good reason.
To answer the last question, yes.
I think everyone should think about death, it's definetly rational and wise to do so.
Life can be beautiful for you now but is a double-edged sword. You don't know if your body will turn on you making non-existence a better option than an existence of pointless suffering. Don't assume you'll always enjoy living, if you are smart and able to do so get the knowledge and the means to CTB painlessly if necessety comes.
Knowing when it's time to die is power and an act of rebellion against the pointlessness of an existence of suffering.