When people talk about Aliens, and how long it would take them to get here, I think they miss the point!
Travelling around the Universe would take forever even at the speed of light.
So for Aliens to visit us they most probably have a way to travel unconstrained by what we know as 3D space and time.
I am not physicist, I have no idea LOL
If we're talking about traveling within our galaxy; the distances and thus sub-light travel times involved are huge, however the time spans available are even huger.
On the timescale of planets, a million years is not "forever" but actually a quite trivial amount of time - if there was an almost perfect clone of Earth on the other side of Milky Way where the evolution of multicellular life happened 1% faster than it did here, then they would be tens of millions of years ahead of us, and that is not only enough to reach us at speeds much lower than c but also enough to colonize the whole galaxy while doing so, spending multiple millenia at each planet before moving on.
Of course this doesn't mean that some advanced civilization haven't figured out how to practically use it, which I'm sure we'll also discover (in distant future) if we aren't killed by something else (most likely ourselves).
It’s even worse than that. Since universe is expanding, there is limited area that is possible to reach with the speed of light. In 200 billion years other galaxies are not going to be visible anymore.
He was saying in the future even with the greatest advancements of technology and telescopes if they look at the sky they won't ever see anything and there will be no clue of there were other galaxies (or clusters, not sure) ever, because of expansion and redshift.
Maybe the aliens have an average livespan of 200k Earth-years. Maybe much more. Maybe they experience time differently, and for them a 100 year journey feels to them like a walk around the block.
Until we know the entire universe (because of the way the universe is expanding this is impossible) we cannot do more than apply our best guess, but I think I hit a good upper limit. Even if I'm off I seems unlikely it is by much.