With foreign_key_checks=0 I can DROP a table, but cannot convert it to MyISAM

CREATE OR REPLACE TABLE t1

(

	a INT PRIMARY KEY,

	b INT

)

	ENGINE = InnoDB

;

CREATE OR REPLACE TABLE t2

(

	a INT PRIMARY KEY,

	b INT,

	FOREIGN KEY (b) REFERENCES t1 (a)

)

	ENGINE = InnoDB

;

MariaDB [test]> SET foreign_key_checks = 0;

Query OK, 0 rows affected (0.00 sec)

MariaDB [test]> ALTER TABLE t2 ENGINE = MyISAM;

ERROR 1217 (23000): Cannot delete or update a parent row: a foreign key constraint fails

MariaDB [test]> DROP TABLE t2;

Query OK, 0 rows affected (0.00 sec)