No it is not ignored. This is easy to test.
DROP TABLE IF EXISTS mytable, othertable
CREATE TABLE mytable(id INT, value1 INT)
CREATE TABLE othertable(id INT, dirtyvalue INT)
INSERT mytable VALUES (1, NULL)
INSERT othertable VALUES (1, 100)
UPDATE othertable SET dirtyvalue = 999
WAITFOR DELAY '00:02:00' /*To give time to run connection 2*/
Connection 2 (whilst above still running)
set value1 = o.dirtyvalue
FROM mytable t
inner join othertable o with (nolock) on t.id = o.id
999 value is used in the update rather than
100 as would have happened without the hint if running at RCSI or being blocked if running at RC locking isolation level.
999 value is never actually committed to
othertable so the use of
NOLOCK here means that the state persisted in
mytable never logically existed.