Nova-ing the star isn't IMO a guarantee of no future contact - there may be other starlines that aren't discovered yet. Also, the SuperHappies may improve their tech over time, and may find ways of no longer needing starline tech.
Also, if there are three civilizations, odds are there are a lot more. The SuperHappies have a better structure to compete and grow with whatever other galactic superpowers exist out there.
In essence, the "closed locked door" is an illusion in my mind. Not something to base strategy on. It is the kind of thing that primitive 21st century humans would think of, and not the kind of option that an advanced 26th century human should consider viable. Were I the Confessor (and by implication, that is the role we 21st century readers are supposed to play), I would zap the Engineer, because he's building a house made of straw and taunting the big bad wolf.
But in the context of the story as it stands, this option is pointless, since the commander has already made his decision. Zapping the pilot is equally pointless, unless no one else is able to move the ship. That may be a defect of the story, or it may be deliberate.
Some quick observations:
#3 is such a big problem that I can't hope to attack it directly - I simply focus on improving productivity and technical innovation in such ways as I can, and I spread the gospel of 'the asteroid will not care how clean the Earth's water is' to people who consider technical degradation as an acceptable strategy for human survival.
(For example, in the remake of The Day The Earth Stood Still, Klaatu claims that 'if humanity dies, the Earth survives', which is such a pile of horsecrap that I still shake my head in wonder at the 'faux-long-term' thinking it represents.)
Now, let's say that in the future, #3 is solved - humanity is essentially immortal, as are the creatures of the Earth. What then? Well, in that case, find a way to remove the 'essentially' from that equation. After that? Dunno. One thought would be: Find a way to edit your memories and place a copy of yourself (or some limited version of yourself) in a simulation of the Earth in the far past, so you can see how you'd live, love and learn in a more primitive time.
There's so much to consider here. For me at least, for something to be fun, I have to know that there's a challenge. For it to be a challenge, there has to be the possibility of failure. There has to be scary parts, that remind you of failure. There has to be multiple real, meaningful, obvious paths that suggest fun in the short term, but disaster in the long term, that you have to look at and reject. There have to be rewards that are enticing, but incredibly rare and difficult, and other rewards that are easier, faster and more localized.
But more importantly, to me, you have to believe it is real - you can't know you're sitting in a fun-generating machine (FGM) - you might wonder about it, but have no real ability to test it.
I can see the possibility of some super-advanced version of me thinking "I want to run a simulation where I live in the 20th and 21st centuries back on Earth", configuring the simulation in various ways, and then "jacking in" to the simulation. All of my memories are suppressed, and 38 years of apparent time later, I'm stuck here arguing on forums with you guys ;-)
Eventually I "die", and the simulation ends, super-advanced me "wakes up" and gets to look at my list of accomplishments and challenges, etc, and chuckle over the choices I've made, in my abysmal ignorance. Then, perhaps, he sits around every once in a while, wondering if his super-advanced life is just a simulation in some even-more-advanced entity's FGM.
It's turtles all the way down.
I too, never wanted to be a stupid teenager, although I never read any books about it. I never smoked, never drank, never used illegal drugs. But I also thought my parents didn't love me. Interesting partial overlap there.
Also, unless a new star has appeared in the last 38 years less than 38 lightyears away, there's no star in the night sky younger than you are, or me, or probably anyone else on Earth.
Like you, I feel maturity is a journey, one that too many people seem to give up very early. I notice at dating sites that some women write "I don't want a man who refers to himself as a 'work in progress'". I understand what they mean - they don't want a man who doesn't know what he wants in life, who doesn't have career goals or a purpose. But what it says (to me) is 'someone who is done changing, learning and growing'.
Which is terrible.