Here's another scenario which is often overlooked:
all of the above is wrong, and aliens are actually extremely nice
(i.e. the moral standards of their civilization are extremely high)

There is still no guarantee though that this will mean anything to the party making first contact with us.

The ones who finally bump into us might be a rogue, pirate or shipwrecked vessel or fleet, not an official diplomatic mission.
They might be in desperate need of resources and not give a damn about what the rest of their civilization think anyway.