That wouldn't be surprising at all. If Obama had been a really stand-out teacher, we'd have heard more about his UC days, so the general silence about him from faculty and students makes a point, but it takes more than hearsay to nail that impression down.
The other professors hated him because he was lazy, unqualified, never attended any of the faculty meetings, and it was clear that the position was nothing more than a political stepping stool.
Again, that wouldn't be a surprise.
But I'd take issue with "hated" which implies some intensity of feeling. If you've got a colleague who's basically a political appointee and doesn't show up for any meetings, you might despise or dismiss or ignore him or not be aware of his existence, but to hate him means taking more notice of him than he deserves.
Also, if you really hated him, you might be tempted to go public if he were running for the highest office in the government. More likely, Obama was somebody who really didn't count intellectually and who the other professors didn't pay much attention to.
If you look at my post #52 it will take you to an article that has comments from quite a number of his colleagues and students.