While technically you are wrong, that is unfortunately what is taught in high school and introductory undergrad biology courses. I would know, because for many years I taught an advanced biology class that covered this subject. Metabolism is one of the pillars of life and the viral factory does very much exhibit this trait. There are viruses that encode some of their own ribosomal components, but ignoring them, all viral factories use ATP in the process of producing virions and other components necessary for their life cycle. That right there, alone, is metabolism. Some virus exhibit additional metabolism by keeping cellular machinery intact after the viral take over. Any ATP that is synthesized after the viral factory's take over of the cell is also a direct result of the viral organism's metabolism, even if all the equipment for this production comes from the cell (which is not always the case).

Every year in the class I taught, the students had to write essays on whether virus was alive or not and not once did a student who picked no manage a passing grade, although my supervisor did insist that he could write a passing one, by negating all of the currently accepted pillars of life and redefining life in a way that also excluded most types of cells (it still wouldn't allow someone to say all cellular life is alive and all viral lfe is not and I always found it humorous when he mentioned it, because Eukarya, including humans, were not alive according to this redefinition of life).

Cellular life is something that evolved here on Earth. When we find extraterrestrial life, it will not be "cellular" as we currently know it, unless this life originated here on Earth and spread elsewhere. Even if there is a non-Earth originating life form that superficially looks like a cell, closer examination will show that it achieves this by different means, because the two will have originated independently. It is equally likely that non-parasitic extraterrestrial life will be found that superficially resembles viral Earth life. The odds of life originating separately and stumbling on the same solutions and processes is astronomical.