No Block Declaration & Eagle Sight

If you declare no block, then can you later after declaring no block play eagle sight to enable you to block even after you have declared no block?

No.

From the card rulings section here on vekn.net:

Non-existant user wrote:

Can be used to overcome the restrictions on blocking (allowing a non-target Methuselah to block a directed action or a non-adjacent Methuselah to block an undirected action). It won't overcome any other restrictions on blocking (like stealth, Seduction, Day Operation, or a prior "I don't block" decision). [RTR 20020501]

We should stop treating Eagle Sight the way we did back in '94.

Name: Eagle's Sight
[Jyhad:U, VTES:U, CE:U, BH:PM3, LoB:PO2, Third:PTz2, KoT:U/PT3]
Cardtype: Reaction
Discipline: Auspex
[aus] +1 intercept.
[AUS] This reacting vampire attempts to block the current action, ignoring the normal prey, predator or target restrictions for blocking actions.

Eagle's Sight is no longer allowing cross-table block attempts, but it is a block attempt. This change happened for V:TES (with a grammar typo, fixed in C:E).

You can't "cycle" Eagle's Sight on your predator's Beaet's bleed with Isabel de Leon (well, you could, but if Beast is lacking stealth, you'll probably enter combat).

You also can't play Eagle's Sight after passing on declaring block attempts.

Pascal wrote:

We should stop treating Eagle Sight the way we did back in '94.

Name: Eagle's Sight
[AUS] This reacting vampire attempts to block the current action, ignoring the normal prey, predator or target restrictions for blocking actions.

I've got lost... What is the actual ruling? Does it allow a Vampire targeted by Seduction to block?

If it does not allow a vampire targeted by Seduction to block, is this kind of Vampire able to play Eagle Sight?

Seduction:
"Choose a younger vampire. That vampire cannot block this action."

Thanks in advance,
Best Regards,
Rémi.

Can a vampire that was the target of Seduction declare a block attempt? No.
Can he declare a block attempt ignoring the normal prey, predatar or target restrictions? No.

Eagle's Sight adds the vampire playing to the eligible blockers of Rulebook 6.2.2.1 "Who May Attempt To Block?", and has him declare a block attempt.

Follow up question, vaguely related.

Player A declares a bleed.
Player B declares no block.
Player A increases the bleed with Conditioning.
Player C plays Eagle's Sight to block.

Argument erupts!
Player A claims that he is able to take back the Conditioning because blocks had been declined before he played it.

Player C claims that Player A has the right to play Conditioning at any time; therefore, he should ask for blocks from the AUS player explicitly first.

Who is right?