That's an interesting theory. I don't suppose that it is based upon any facts or knowledge, but merely speculation, which is all we have to go on.
Let's speculate, then. If you were an adcom at Oakland, who would you skip?
Let's take the high end applicant. He has a 36 MCAT and a 3.9 from an Ivy League with excellent EC's and published research. He has no association with Michigan or Oakland university. If you were an adcom, would you waste your time interviewing this guy? He obviously applied to Oakland as a safety school, just in case. Conversely, would you interview him and, if he had good presentation skills, would you offer him some incredible financial deal in order to raise your school's first year stats?
But.... what if you have 100 of these applicants (which is likely). You know that some of them might attend, but 90 of them won't. You want the 10 applicants for stat reasons but you don't want to waste your time interviewing all 100.
The best way might be to not offer interviews to them until December. At that point, more preferred schools have made offers and the ones who are not serious about Oakland would withdraw.
This is speculation, but it might be a good explanation for the slowness of their interview invites.
