A typical nucleated Boltzmann brain will, after it finishes its activity, cool off to absolute zero and eventually completely decay, as any isolated object would in the vacuum of space. Unlike the quantum fluctuation case, the Boltzmann brain will radiate energy out to infinity.
After concluding its function, a typical nucleated Boltzmann brain will cool off to absolute zero and ultimately decay completely, just like any other isolated object in space. In contrast to the quantum fluctuation scenario, this brain will radiate energy outwards without bound.