By law, I suppose not. Morally, it depends on whom you ask. If it were open source, other people could pick it up (gratis or for a fee). Right now, nobody can

By law, I suppose not. Morally, it depends on whom you ask. If it were open source, other people could pick it up (gratis or for a fee). Right now, nobody can (except for Microsoft), because it is proprietary software. Microsoft brought it upon themselves to release the software as such.