It is pretty daft because it doesn't provide any basis for comparison.
If you put a concealed speed camera on a road and it caught one motorist every other day, that would be hounded out as a rediculous waste, whereas if it was a "cycling camera" it becomes a moral panic.
For instance, "30 fines were handed out in the Meadows in a two month enforcement period" (paraphrase), but we know from the Spokes survey that somewhere around 300 cyclists pass north/south there every rush hour - so not including weekends, the enforcers issued 30 tickets out of almost 30,000 journeys, or 0.1%. That's assuming that *nobody* cycles there at weekends or outside of rush hour, and that none of the tickets were for cyclists going east/west...
I think a better way to argue against this sort of thing is not that the enforcement shouldn't happen, but there should be proportional enforcement (for instance, assign policing hours based on a ratio of reported collisions). It doesn't matter how it's worked out because cycle enforcement will never pass that cost/benefit barrier even if cycle use became near universal...
It is what it is - an outgroup being leaned on. Whether there's justification for the police time is so secondary it's irrelevant.