If I understand your code, both nominationType and userContext.UserGroupRoles are already fetched so you have the data in-memory. If that is true, you don't need LINQ2LLBL, just Linq2Objects. So you can do something like:
bool toReturn = nominationType.NominationType_Role.Where(ntr =>
userContext.UserGroupRoles.Select(ugr => ugr.RoleId)
.Contains(ntr.RoleId)).Count() > 0;