Merit Badge Counselors can choose to restrict their listings in the MB Counselor Search to Unit, District, Council or Worldwide. Because of this, a Counselor that sets listing preference to Council will only be visible to units in that Council. To be visible to neighboring Councils, the MBC must set the listing preference to Worldwide.
Scoutbook respects the wishes of the MBCs, thus you cannot search for an MBC out of Council that has not set listing preference to Worldwide. The Council drop down is read only for all users except Council Admins that serve in multiple Councils.