I guess the distinction between scientific hypotheses and scifi that extends beyond well understood science is that you have to have scientifically rigorous reasons to think the hypothesis might be true. So not mere notions, e.g. there is no cold fusion reaction hypothesis anymore.
I guess it simply shows that atuhtority is the most important quality you need for breakthrough ideas and whether you are doing science or writing fiction is not so relevant :)
Imagine planting many acres of genetically-modified trees and coming back in forty years to the primary structures of thousands of beautiful forest homes :P
EDIT: Might even lead to interesting "composite materials" if you can get different wood types to (semi)fuse together naturally.
My guess is you would use Dyson Trees inside hollowed out asteroids that are rotating, with the axis of rotation constantly pointing towards the sun. The window that lets the sunlight through (and keeps the new atmosphere in) could be adapted so the trees do not get too hot.
You could also have an asteroid on a circular orbit around the Sun at a distance of 1.7AU. There, in constant daylight the temperature should be just right (300°K, 26°C) when constantly facing the Sun.
Trees/plants still respire, so they would need some sort of atmosphere to be present within the comet. But if it's sealed so that gases don't get out, how does sunlight get in?
Not to mention that the whole plan goes bottoms up if the comet just happens to pass close enough and most of it evaporates into space. There goes your "tree" along with it.
I love the idea of a Dyson swarm. Just build some self-replicating factories on Mercury for building sun-orbiting PV arrays and our energy problems are solved for the next million years or so! Short-sighted argument against doing this at.
I've skimmed the follow-up article and I'm not going to read it in depth to avoid spending the morning shouting at clouds.
Anyway I digress. Self-replicating factories sound great but eventually they're gonna start evolving no matter how tightly we try and lock them down, at which point we'd better hope the planet we're living on doesn't look too much like lunch to them. (I'm picturing the Greenfly mentioned in some Alistair Reynolds books.)
The linked article made me think that perhaps it is possible to create a new species of a tree that would bootstrap this change naturally. With new gene editing methods, it should be possible to combine features of different plants to do this.
Star Trek was, what lately has been, TBBT making people love sciences, space, and dreaming big.
The same applies for the word "Dyson". I may have lunch with a Bob Dyson, but the word "Dyson" will always bring Star Trek and Dyson sphere in mind :)