I found something. It could mean something or not:
"When a ship suffers damage, it suffers that damage one point at a time. For each point, you reduce the shields in the defending hull zone by one. If the defending hull zone has no shields to lose, deal a facedown damage card to the ship instead." (Bold added)
So, in fact, the ship does not do anything with the shields. Who suffers damage is not who reduces shields (you-rule applies for upgrades and squadrons, not rules). He just can choose the hull zones where the damage is suffered.
"Redirect B: The defender chooses one of its hull zones adjacent to the defending hull zone. When the defender suffers damage from this attack, it may suffer any amount of damage on the chosen zone’s shields (up to the shields remaining on that zone) before it must suffer the remaining damage on the defending hull zone."
I know, the ship still suffering the damage and the ship doesn't treat itself as having no shields but...
"Ships and squadrons can suffer damage from attacks, obstacles, and other game effects."
So technically we have sources of damage (attacks, obstacles, abilities, face up damage cards...). That sources has rules depending on its nature (squadron's attacks don't sum crit icons). Luke's attack is a source and it "ignores" shields. When the ship redirects, the source still being Luke's attack so, no shields, sorry, take the damage. When the ship resolves a face up damage card, the source is the damage card and it doesn't ignore shields.
What do you think?