I wish they would have communicated.
I think things that could have affected them include everything from: changing laws, possible security breach(I initially spelled breath haha), maybe they were a part of the samurai wallet fiasco. The list goes on. It seems they needed to put distance betwen them and the site. the question is why.
All that you mentioned is correct and valid, and I know you said that the list goes on, but another possible reason worthy of a mention is "lack of enthusiasm to continue on the freebitco project". Because believe it or not, every one who runs a business or a project usually gets to this point where they completely loose interest in the business, reasons vary for different people..
Some people, they may loose interest because they've made much more than enough money and see absolutely no reason so keep running the project, this is especially true for those who their goal for starting the project was to make money, when they finally get the money, it's easy for them to loose interest in the project specially if the project is not allowing them enough time to enjoy the money they've made.
For others, it's lack of success, when they run a project for a long time and they are not achieving the desired goal, its easy for some to get fade up and eventually give up, this might not be the case of those behind freebitco but it's good to mention it.