Maybe they are smarter than we think, and know that it isn’t quite “time” yet for this dish to be pulled out of the oven?
To formally raise the issue prior to Congress' comfirmation of Obama would create a deadline by which he must either (1) present documentation showing he is legitimate, (2) be disqualified for failing to show documentation, or (3) be allowed in despite failing to show documentation. Amendment 20 would allow a means by which none of those things would have to happen on any sort of timetable. If Obama never wants to release his documentation, he could remain Presdient-Elect for four years without having to show it, and never have to actually be disqualified. Biden would serve as Acting President in the mean time.
How would that not be the most elegant solution?