Two cars can be driving along at identical speeds, and the windows may be so blocked up that they can only see each other. From their relative perspectives, they aren't moving.
Reality, however, cares not a whit for their relative perspectives, and as the two cars cruise through the roadblocks and off the broken bridge, the occupants will soon learn that painful lesson.
So you can claim that the appearance of motion is relative, but the reality is that appearances don't matter to the actual facts.
Being stationary is contained in the total spectrum of movement, zero velocity. Samne math, same equations, same physics, same continuum.