Nope.You need to read it again.
(a) The end of a quarter occurs when any field Umpire or emergency Umpire first hears the siren sounded by the Timekeepers to signal the end of a quarter. The field Umpire shall acknowledge the siren and bring play to an end by blowing a whistle and holding both arms above their head.
Literally says that the Umpire must hear the siren and then the play ends when they blow the whistle and hold both arms above his head. I have bolded it if it still confuses.
“The end of a quarter occurs when any umpire first hears the siren”. The subsequent signals are only to tell everyone play is over. We literally see this all the time on line-ball calls (like this one) - where the ump takes a second or two to physically blow the whistle, they are still able to void kicks that occur in that time. Most famously in a draw between Hawthorn and GWS in 2017 when this was put under the microscope.
I’m an ex umpire - I know exactly what I’m talking about. This is a myth.