Galactic Police?

How the Galaxy would be policed through time travel would be to easily maintain whatever time line was wanted.

The way this would be done is to find those individuals causing trouble to time lines and either convince them not to do what they were doing. Or to simply go back to when they were conceived and radiate the father so all his sperm died that day or to radiate the father's sperm before it was inseminated into the mother. In this way you would eliminate all pain at all from anyone (unless they were an intuitive) because all physical causes for any pain in anyone would be prevented. And anything that needed to be done by that individual could be done by a specially designed robot that could "grow up" in place of that individual as a lifelike android to do all the necessary things without doing harm to the planet or time line.

By doing things like this even people like Hitler, Stalin, Pol Pot and others could be prevented before they were even conceived or born. This is how I believe this has been done since World War II through now and into the future by Galactic Police specializing in preventing large wars or nuclear conflicts here on Earth. This could be done by Galactics who have humanlike forms or by training "Men in Black" types of individuals to do this.