Instead I found this odd observation from The Journal of Police and Criminal Psychology, March 1993:
Height of the assailant is also a factor; police officers are more likely to be assaulted by those of a small or medium height. Bixler (1976) for example, found over 70% of police assailants were of a small or medium build...
Perhaps this is related to the fact that, height correlates with health and wealth: the good nutrition and safe environment experienced by a wealthy child contributes to growth. The study also remarks that assailants of police are from 'lower socioeconomic levels' or unemployed. If poorer people are shorter, and poorer people are more likely to attack police, then perhaps there is no other association between shortness and violence towards police than their poverty.
The other possibility of course is that shorter men were suffering from Napoleon Complex, an insecurity due to short stature that pushes them towards violent behaviour. But one study by the University of Central Lancashire suggests that no such complex really exists:
So perhaps short people are doubly unfortunate. Underpaid and poor, and if they ever react with aggression, derided for having a non-existent Napoleon Complex. Ouch.
Men of different heights duelled with wooden sticks but one of the subjects deliberately provoked the other by rapping them across the knuckles.
Heart monitors revealed it was the taller men who flew off the handle more quickly and hit back....
Dr Eslea said: "The results were consistent with the view that Small Man Syndrome is a myth.
"When people see a short man being aggressive, they are likely to think it is due to his size simply because that attribute is obvious and grabs their attention."