The com/sun/nio/sctp tests are run when running the jdk regression tests with the makefile in the jdk/test directory. They are currently part of the jdk_nio3 target.
SCTP is a niche area and there is no need to have these tests run with the nio tests. Also most of them are on the ProblemList.txt since there are many kernel issues ( most of which are resolved in the latest Solaris 10 update release, but there sill remains a few that will be addressed in S10u11 ). The bottom line is that these tests are not suitable to be run in JPRT, and give little value to developers not actively developing SCTP.
Best to provide a specific jdk_sctp target that can be used when the sctp tests are required to be run.