Two things:
1.) It is not competing business with Craigslist, does not provide the same service(s), and (technically) does not use the same name. A crafty attorney could work around this easily. The proper name Craig could easily be the name of a friend of his from high school who was influential in his life. The burden of proof is on Craigslist is to differentiate this guys moving business as being just for Craigslist customers. If he got paid even one time to move something for someone that was not purchased on Craigslist, exclusivity is void.
2.) It can be argued that this individual actually helps bring awareness to those who might never have utilized the services of Craigslist. It is free advertising for them.
As an attorney friend of mine has said to me about lawsuits; the goal of a lawsuit should be about the money, and not about anything else. Those who sue simply because of principal, or ticky-tacky crap like this, are doing so to satisfy their own control-freak agenda, and clog the courts with frivolous crap. This guy has no money, and there is no basis to use this case to set a precedent. This is clearly a case of an attorney for Craigslist simply doing something to justify his slice of the payroll, and nothing more.
Big company sues little guy for nothing but trying to help out their customers? Help us out, and we will punish you for it. Great company mission statement.