A couple of things to consider:
* 5 year olds are going to be afraid of you...regardless of how many of them there are. Once you hurt one or two of them pretty badly, then they are terrified of you. It would be them running from you, not the other way around. (EDIT --- Okay, I just read the rules again, but still...)
* For 99+% of the population it would be EXTREMELY difficult (psychologically) to hurt a five year old that bad. The first one would be horrible, the second would be worse. By ten, you'd probably be okay with it
* Why are people wanting to avoid the herd of kids that will inevitably form (think of a 5 year old soccer game, just one clump of kids regardless of how much training they have)? Run into it knocking many over and knocking their heads together.
* Remember that their number is always diminishing. So, for example, for those saying 100 --- the question isn't whether 100 kids could take you when you get tired. The question is whether (maybe) 50 could. You drop them at a faster rate than you tire. It would take SO little effort to incapacitate them.