AtD translation: Through dusk’s reassembly of the broken day therefore

[Mike Jing]

P213.17-24   Reef shelled out the pesos without haggling, not too surprised
at the existence of the silent market, for enough survivors must always
want to scale the forbidden walls, unwilling to leave matters to the
mercies of Jeshimon. Through dusk’s reassembly of the broken day therefore,
as the first star appeared, Reef found himself in growing desperation
swinging iron hooks lariat style, trying not to be in the way when he
missed the rim of the tower and they came falling back through the dark to
clang in the beaten dust.

In what sense is the word "therefore" used here?