Ok, first of all, it was reduced to a 23 day sentence. That wasn't speculation. Look up "paris hilton 23 day" on google, and a number of news sources will confirm that. Second, I agree that having the sentence reduced for "good behavior" was inappropriate, but once it was done it should not be reversed.
Third, I think it's obvious why the sheriff re-assigned her.
And finally, this is an issue of someone getting special treatment because she is a celebrity and also getting unusually harsh treatment for the same reason. Her initial prison term was longer than usual, and it was extremely unprofessional to lengthen her jail term after it had been officially reduced. On the other hand, the sheriff's treatment seems preferential and it was strange that her initial jail term was reduced for "good behavior" without really having any time to show good-behavior.
Now it's become a matter of the public venting their general outrage and hatred towards a nonsense garbage news story because they're bitter about not being privileged too. The whole thing is disgusting.