Ah, the way I see it is that these things are handled automatically. So what you are talking about is providing special case behaviour for a single field in the user object. Its possible sure, but its not straight forward. Its definately not a whip out a patch in 30 minutes (or 2 minutes for that matter) that it might be in some scenarios. Yes, I personally as a pmdever will look into it, no I did not see a clean and obvious patch to do it when I first looked after reading your node.