This is making it sound way more complicated than it is. Sibling comment is much better. Thing changes over time -> thing experiences time -> it's not going the speed of light -> it has mass.
And a nuance that is easily lost: the different neutrino eigenstates/flavors travel at different velocities, because they have different mass, so the probability of detecting one flavor depends on the distance travelled.
Essentially each neutrino travels in three different "waves", but is still one unit in a constant superposition between the three.
Essentially each neutrino travels in three different "waves", but is still one unit in a constant superposition between the three.