And heres some evidence btw.
XCom stands for Extratrestial combat. I.e. fighting things that arn't from terra or earth.
XCom is a mordern style name based on late 80s culture for 'action' based orginisations (X-Men being a great example).
AlienShock is set in the 50s, just like BioShock. If an orginsation was setup in the 50s to research and fight aliens it would be called something like "the Institue for Threats of Unknown Origins" or ITUO.
Xcom does NOT fit with the setting (which they have a THIRD game using a similar setting - i.e. very little research to do).
All the games use the same weapon mechanics and interfaces. Remember you always had allies in BioShock.
Its just AlienShock.