Yes agree.
I think i cannot achieve this task using pg_dump.
Another way i thought of is,

Dump

create table c_order_A as (select * from c_order where period=2009 and org <> 'A')
pg_dump -T c_order MyDB > dumpfile
# -T exclude table c_order
delete from c_order where period=2009 and org <> 'A';
delete from c_order_A;
drop table c_order_A;

Restore

psql MyDB < dumpfile
insert into c_order (select * from c_order_A);
delete from c_order_A;
drop table c_order_A;