NOT IN correlated sub-query has unnecessary join

select count(*) as c
from "scott".emp as e
where sal + 100 not in (
  select deptno
  from dept
  where dname = e.ename);

EnumerableAggregate(group=[{}], C=[COUNT()])
  EnumerableCalc(expr#0..9=[{inputs}], expr#10=[IS NOT NULL($t7)], expr#11=[<($t5, $t4)], expr#12=[OR($t10, $t11)], expr#13=[IS NOT TRUE($t12)], expr#14=[0], expr#15=[=($t4, $t14)], expr#16=[IS TRUE($t15)], expr#17=[IS NULL($t2)], expr#18=[OR($t13, $t16, $t17)], proj#0..9=[{exprs}], $condition=[$t18])
    EnumerableJoin(condition=[AND(=($1, $8), =($2, $9))], joinType=[left])
      EnumerableCalc(expr#0..5=[{inputs}], expr#6=[IS NOT NULL($t2)], expr#7=[0], expr#8=[=($t4, $t7)], expr#9=[IS TRUE($t8)], expr#10=[OR($t6, $t9)], proj#0..5=[{exprs}], $condition=[$t10])
        EnumerableJoin(condition=[=($1, $3)], joinType=[left])
          EnumerableCalc(expr#0..7=[{inputs}], proj#0..1=[{exprs}], SAL=[$t5])
            EnumerableTableScan(table=[[scott, EMP]])
          EnumerableAggregate(group=[{1}], c=[COUNT()], ck=[COUNT($0)])
            EnumerableCalc(expr#0..2=[{inputs}], expr#3=[IS NOT NULL($t1)], proj#0..2=[{exprs}], $condition=[$t3])
              EnumerableTableScan(table=[[scott, DEPT]])
      EnumerableCalc(expr#0..4=[{inputs}], DEPTNO=[$t2], i=[$t3], DNAME=[$t4], SAL=[$t0])
        EnumerableJoin(condition=[=($1, $2)], joinType=[inner])
          EnumerableCalc(expr#0=[{inputs}], expr#1=[100], expr#2=[+($t0, $t1)], SAL=[$t0], $f1=[$t2])
            EnumerableAggregate(group=[{5}])
              EnumerableTableScan(table=[[scott, EMP]])
          EnumerableCalc(expr#0..2=[{inputs}], expr#3=[true], expr#4=[IS NOT NULL($t1)], DEPTNO=[$t0], i=[$t3], DNAME=[$t1], $condition=[$t4])
            EnumerableTableScan(table=[[scott, DEPT]])