Why isn't this predicate being pushed down to TableScan?

[aprimadi]

query TT
EXPLAIN
SELECT *
FROM join_t1
RIGHT JOIN join_t2 on join_t1.t1_id = join_t2.t2_id
WHERE join_t1.t1_int IS NOT NULL
----
logical_plan
Inner Join: join_t1.t1_id = join_t2.t2_id
--Filter: join_t1.t1_int IS NOT NULL
----TableScan: join_t1 projection=[t1_id, t1_name, t1_int]
--TableScan: join_t2 projection=[t2_id, t2_name, t2_int]

[alamb]

I agree the filter could be pushed into the table scan

----TableScan: join_t1 projection=[t1_id, t1_name, t1_int] Filter=join_t1.t1_int IS NOT NULL

Perhaps it is because the predicate pushdown optimization pass is run before the pass that pushes filters through joins?