After some thought, I'm still unsatisfied with "status" as an explanation of the phenomena. If we must use Hansonian terminology, I think the better explanation is signalling - specifically, signalling tribal affiliation. "who you wish to associate or disassociate" is either very imprecise or circular.
Additionally, I'm uncertain about Hansonian analysis of this phenomena because it makes the thought processes seem so deliberate and considered - when real world examples don't seem all that reflexively considered. I'm doubtful that people hostile to French Muslims could produce a coherent explanation on demand, and if you waited for them to collect their thoughts, they'd say things isomorphic to "Muslims in France are behaving unFrench." (whether that is the same thing as in-group bias is a separate question - I do think your explanation of in-group bias artificially narrows its scope)
A thought occurred to me today as I skimmed an article in a rationality forum where the subject of gay marriage cropped up; seeing as the issue has been hotly contested in various public fora and especially the courts, what about poly? After all, many if not all the arguments for gay marriage apply to poly marriage as well.
Questions for LWers who are currently in a such a relationship, or have an opinion to share:
Do polies want to marry each other or do such relationships not lend themselves to permanence above a threshold of partners? Should polies campaign for the right for a civil union anyway? what are the up and down sides of this? etc