Agreed, but stars are very fragile in some ways; surprisingly small disruptions in some of their transitional layers can cause novas. Stellar modeling is entertaining in that way.
So in place of "dismantle star" perhaps "provoke extreme mass loss" would be a more obviously net energy-positive goal for the engineers. Still, one should run the back of the envelope calculations on what you'd have to do with a stellar mass to produce greater energy than it emits in its current form, and whether the difference can be enough to make it a net positive to nova the star. My intuitive belief is that the difference in efficiency of use of materials can be huge, more than enough to justify large investments in stellar engineering at the stage when technologies means molecular nanotechnology plus nucleosynthesis: factories capable of taking in hydrogen and turning out anything.
So in place of "dismantle star" perhaps "provoke extreme mass loss" would be a more obviously net energy-positive goal for the engineers. Still, one should run the back of the envelope calculations on what you'd have to do with a stellar mass to produce greater energy than it emits in its current form, and whether the difference can be enough to make it a net positive to nova the star. My intuitive belief is that the difference in efficiency of use of materials can be huge, more than enough to justify large investments in stellar engineering at the stage when technologies means molecular nanotechnology plus nucleosynthesis: factories capable of taking in hydrogen and turning out anything.