Is light of pulsar spreading in superluminal speed?

This post is a reaction to recent PW article Pulsar bursts move 'faster than light'. It's not true, this phenomenon was described in an astronomical object first - the same effect was disputed before years for motion of bright areas in jet of M87 galaxy, where it has supposedly the same explanation. As a dense aether proponent I appreciate readers, who are trying to think "out of box" - but in this case, this particular observation has really nothing to do with Aether and "violation of Lorentz symmetry" - but with peculiar way, in which light of pulsars propagates through environment filled by particles of interstellar gas. The animation bellow illustrates it by computer simulation:

This phenomena is related to way, in which light is propagating through so-called metamaterials. The uncertainty about exact source position is the reason, why we cannot talk about information exchange between observer and object, because the amplitude of light travels through interstellar gas in noncausual way. After all, it's not wave itself (group velocity), but an amplitude of light (phase velocity), which is traveling here by superluminal speed in analogy to motion of laser spot along surface of moon. The supersonic sound wave "spreading" was observed during spreading of ultrasound pulses through dense polystyrene dispersions in water, too.

A more intriguing question could be, whether longitudinal component of CMB noise - i.e. superluminal gravitational waves could be interpreted by analogous dispersion of light waves on Higgs field forming vacuum. In this moment I'm unable to decide, whether such perspective is relevant to reality and if it could lead to some new testable predictions. It could be somehow related to so called block-universe concept, by which reality in motion occurs by inhomogeneous spreading of information through Aether lattice at rest - which I personally consider biased toward atemporal perspective of Universe.