It wouldn't matter if it was 50 degrees at each layover, a poorly written attempt wrt the definitions, however I cannot think of one sector on any fleet in mainline where jackets aren't mandatory.
It might be acceptable if it's 40 degrees in Perth, to have it off walking to the terminal, but once inside, jackets on.
Also a clever document that enables the stand down provisions to stick if non compliant in any way.
And no.that last bit isn't a joke.