Or would you seriously believe anything they believe is real alien activity would be declassified ?

They compare to standard concrete while several higher strength concretes even way beyond their performance is available. So it is all about price or sustainability they could improve. And ground coffee is not available on any relevant scale. They used the unusal 75 mio kg notion instead of 75 000 t and missed to give that australias concrete production is 29 mio m ~ 70 t as reference, so even in most optimistic collection scenarios less than 1% could benefit from their research. Not to mention that ground coffee is not produced in industrial scale facilities but at home, offices and coffee shops: All small scale places and therefore high effort to establish collection. Transport will ruin even any remaining sustainability claim.