The project is dead because despite being a useful idea, the volume of test scenarios needed to fully implement LINQ in a reactive way is very high, and it never got the take-up it needed to make it worthwhile to maintain.
Consider the ordered scenario above (assuming it didn't have the bug). How would you do that without Bindable LINQ?
1. Property changed event on every item in the collection
2. Remember to attach/detach property changed handlers when the collection changes
3. On collection change, ensure added items are inserted in the right place in the ObservableCollection you projected it to
4. On property change, move items around in the collection (raising a Removed event, followed by an Added event at the right index)
Make sure you use weak event handlers for all of those events as well, so you don't get memory leaks.
There are UI's that need to do this (I worked on one before building Bindable LINQ - that's where it came from). It is error prone, complicated and verbose code. I'd hate to still be writing it by hand.