The supposed experts are pushing to have MATS "clarified" so that MATS 4.5.2.2 "Aerodrome controllers may also separate by the use of visual observation of aircraft position and projected flight paths" is interpreted to mean:- "If I see to aircraft diverging away from each other and they subsequently are lost from view, then they are separated because I projected (anticipated) that they will achieve procedural separation at some point, regardless of whether or not they were procedurally separated when I lost sight of them"
From my reading the procedure indicates "visual observation of aircraft position AND projected flight paths" meaning you MUST be able to see the aircraft AND (meaning at the same time not or or either) the controller anticipates the flightpaths will diverge such that an unsafe situation does not develop.