This is really fascinating to me. Since they are fraudulent anyway, why wouldn't they just say they are a recruiter from Google and get you to accept their connection request. Do they get more responses by claiming they are Nigerian Princesses?
There was a study (sorry I can't find the link) few months ago that discussed how spam looks bad intentionally. The idea is to weed out the smart or even average guy and just get the person that are a good target for this kind of con.
http://research.microsoft.com/apps/pubs/default.aspx?id=1677...
Edit: Here's a particularly illuminating quote: "By sending an email that repels all but the most gullible the scammer gets the most promising marks to self-select, and tilts the true to false positive ratio in his favor."