You're thinking of the wrong kind of relativity. The neutrinos aren't "bound" to any frame. They just move from A to B. The (apparent) distance between A and B changes depending on the observer's frame of reference, as does the (apparent) time it takes them to get from A to B. The faster the observer goes, the shorter the apparent distance (Lorentz contraction) and the smaller the apparent time (time dilation) become. But the RATIO of the apparent distance from A to B to the apparent time it takes light to travel from A to B remains constant. So if the neutrinos are moving faster than light, they will appear to do so as measured from any frame of reference as long as you're consistent about using the same frame to measure time and distance. THAT is where it gets tricky because the GPS satellites that they use to establish both time and distance are all moving in different frames. You also have to take gravity into account because the emitter and detector are non-intertial frames.