I wonder whether ATCOs would benefit from attending the CRM days with pilots?
I wonder whether the ATCO in question does any flying? On balance I doubt it.
Giving the "heads up" on the potential conflict was merely exercising a duty of care.
How would the pilot have felt if by keeping silent something far worse had arisen? He did exactly the right thing.
The ATCO was saved having to complete all the papaerwpork. He could be grateful !!