They definitely need to cut down on the number of services available, and the number of user accounts. This one is by far the hardest to deal with in many ways. A really determined attacker can simply set up a server and ask to join the Suidnet IRC network. This issue boils down to carefully vetting server administrators and making sure they are trustworthy. The good news is they seem aware of the current problems and are working on them.
Security is an ongoing process that never ends.
We originally started Suidnet just so we could talk to one another encrypted and didn't really expect much more users on the system besides us. The main goal is to provide a IRC network where you don't have to worry about people listening to your conversations. To provide the facility for people to trust that their conversations are only heard by those they are intended for. I think that they will. It has already been widely implemented in many Unix clients, so it seems only natural that more and more clients will begin to support it as it grows more popular.