You don't understand how big the proposed expansion at Abbott...

You don't understand how big the proposed expansion at Abbott Point is. It's an upgrade from 50 to 385million tons per year. Rio is/was only one of many stakeholders.
T1 is already operating and Adani is looking at increasing it to 85 mill tons.
Hancock Coal and BHP Billiton are involved in T2 & T3
T4-T9 would be 30 mill tons each and the six companies chasing those are Anglo American Metallurgical Coal, MacMines Austasia, North Queensland Coal Terminal (consortium of Macarthur Coal, Peabody Energy, New Hope Corporation, Middlemount Coal and Carabella Resources), Rio Tinto Coal, Vale and Waratah Coal.

So Rio is/was only a small part of the whole Abbott Pt project.

"I am sure BoA didn't snap up 7% of CLR for some stranded coal (however good the quality) that in the best scenario will not make it to market for many years"

Read the substantial shareholder notice again and you'd see that BoA did not snap up 7% of CLR at all.
They bought 5 million shares and BORROWED 5 million (approx).
Why do you think they borrowed the shares?

As for your comment about stranded coal ... check a map.
CLR's tenement is located very close to existing (and proposed) rail infrastructure.