Pst, don't spoil the ending by telling everyone too much
You're right about the ending though, I noticed that too. I guess they were too lazy to take that into account, it would be a lot more complicated that way.
Speaking of crappy soldiers, I also used to sack soldiers with very low TU, like 50 or so. While it doesn't matter for firing (that takes up a fixed portion of a unit's TU), it makes quite a difference when walking.
And if you're using units with low TU, let them be followed by one or more with very high TU: that way, if the first runs into an alien, the other(s) can still take a shot at it.