The concept of the Alpha unit is probably well known.  One was even a public entity that accompanied Terra Venture.  Whether or not that level of public knowledge carried over enough for random people to attach the catchphrase to what appears to be a person I'm not so sure about.  Corvo,<em>maybe</em>, has a better understanding.  Alpha's from his homeworld using a techbase he's more familiar with.  But it may not have clicked yet that "hey, this is a robot in disguise" yet.  Things are just super chaotic right now.