(I haven't seen this episode, but I think I can clear up a small point about the light-years thing without having actually seen the episode.
If the star was 2.2 million light-years away from us, then (assuming relatively flat space-time between the Earth and the star), the light from the star would take 2.2 million years to get to us, traveling at the speed of light. I think that what Peter MacNicol's character was trying to say was simply was that (a) the star died 2.2 million years ago and (b) the star was - not at all coincidentally, but in fact, precipitating his character's statement causally - 2.2 million light-years away from the earth, so that "news" of that event was just reaching the Earth now.
That's really the idea behind astronomers using light-years - at first, a bizarre unit of measurement, possibly - as a unit of distance: if a planet/star/etc. is X light-years away from the Earth, "news" about the heavenly body that has reached us via light waves emanated/reflected from the heavenly body will have actually happened X years in the past. The use of light-years as a unit of distance makes such calculations as how long in the past a celestial event we are just now "observing" actually occurred essentially trivial.
There is a system of units in physics, called "natural units", in which the value for c - the speed of light - is simply 1 (with units of velocity, length/time, of course); this makes some calculations - "E = mc^2", for instance - as trivial as the one I outlined above. Converting numbers gleaned in such "natural units" to numbers in the metric or English systems most of us normal humans use in our daily lives, actually creating jet engines or elevator motors or whatever engineering application of physics we are doing, a drag, but it makes the physicists' lives simple(r).
Hope this help.)
