  Thompson et al. (Reports, 1 November 2019, p. 637, Science) interpreted the
unseen companion of the red giant star 2MASS J05215658+4359220 as most likely a
black hole. We argue that if the red giant is about one solar mass, its
companion can be a close binary consisting of two main-sequence stars. This
would explain why no X-ray emission is detected from the system.
