Contrary to what you may beleive, most of the active users are not little impressionable kids, most users are in the teens. And in my opinion, seeing a word being used on the Internet isn't going to scar a child for life. I learned the B-word when I was 7, and it never impacted me in any way.
I personally do not beleive infractions should be thrown out at the use of a single swear word, but if someone is known to swear excessively, then something should be done.
I also beleive that the filters here are too strict. Some words that really aren't offensive are blocked. I can't say them, obviously, but the filters should be reviewed.