Well, it could be made to be a variable scoped outside of the view too, but it made sense to me at least as a class variable, since it's data that would be shared between instances of that class.

HTML5 drag and drop does have a mechanism for passing data between drag/drop events, but sadly it is at least not obvious to me that that can be used for passing references either.

If there was ever a reason for Aloha to use the code and there was no other way to pass the reference, we'd probably pass the id of the element and then do a lookup to get the model.  However, I'd be more inclined to make that an 'in addition to' feature (only perform the lookup if it doesn't already have the reference), since it's obviously a performance hit to no search at all.