I don't see anything about her on vacation in Hawaii anywhere. Maybe we're talking about different sites?
The Casey Anthony Boycott Information site that I checked said they were receiving death threats because so far the boycott efforts were successfully keeping Ms. Anthony from brokering a deal. They even claimed to have filed a police report.
If that site is accurate and whatever site you're referring to is accurate, maybe whoever paid her vacation expenses did so in fear of their lives due to her tantrums and fits of rage.
The information about her going to Hawaii is (was) in the comments re the article on Roy Kronk's lawsuit . Yesterday they posted a photo said to have been taken by her in Hawaii and detailed that this was an all expenses (paid by McKenna P.I.) vacation, according to her Twitter posts. When I looked a while ago they have retracted that statement as they are not sure of the source..