What does the statement "an abnormal reaction to an abnormal situation is normal behavior" mean?

I think what this interesting and thought-provoking
statement is trying to suggest is that if a situation is "abnormal" or out of the realms
of our experience and undestanding, it is therefore "normal" to react "abnormally" to
it, because it is so abnormal. This statement uses a double negative to suggest a
positive, by stating that two abnormals together create a normal. I suppose it makes
sense if you think about it. Let us just take an extreme example. If aliens invaded the
planet, this would definitely be an abnormal situation. In response to this, we would
expect people to act abnormally, crying, screaming or showing extreme emotion. However,
according to this statement, this would be a normal reaction because of the abnormality
of the situation. Normal reactions are reserved for normal situations which we
understand and can interpret. It is only normal therefore, for an abnormal situation to
produce an abnormal reaction, which would cancel out the two abnormals making the
response normal. If you get what I mean!