Delaying a 142 rail bus service full of passengers all squashed in shoulder to shoulder in the heat who can't wait to get off for the sake of a freight train hauling containers just seems wrong. The containers aren't suffering.
Depending on the freight traffic, it might very well be suffering. Refrigerated containers have an on board generator to run the refrigeration unit. If the container is too late arriving, then the generator will run out of fuel and the contents of the container may be lost. Another historic - and extreme - example was molten steel from Middlesbrough to Consett, which I believe had priority over East Coast expresses because if the train was delayed, the steel would solidify, the specially built wagons irreparably damaged, and the Consett steelworks forced to close.
Speed doesn't really correlate with how time critical something is - some of the most time critical traffic in the UK is carried over the final part of its' journey by a person pushing a handcart for several hours. Yet when it's on rail, that same traffic is given top priority.
Some traffics may not be time critical, depending on the size of the buffer at the destination. Coal traffic used to be like this, because of the requirement for power stations to hold several months' worth of fuel in reserve. But coal is basically gone as a bulk traffic; biomass might work this way, but I'm not sure. Oil may or may not, depending on the cargo. Anything forming part of a retail or manufacturing supply chain is almost certainly time critical.
But freight pays its way too. The only way that 'holding' freight could be justified was if it was charged substantially less than now, which would reduce income to the railway.
Unlike passengers, freight actually
does pay its' way. Since freight is unsubsidised, it only runs when it's profitable to do so. That includes paying Network Rail for the paths. Virtually all passenger operations run at a loss and have to be subsidised. From a strictly economic point of view, the freight operators should have first pick of the paths and the passengers fit around them.
This, of course, is
exactly what happened in the 'golden age' of rail travel, with many fewer passenger trains running at irregular intervals to fit around the freight timetable.