Leviathan vs Seven

So a turn goes as follows:

Opponent has Seven and Ace on the field.

I have Yuna and Tidus on the filed.

Here is the turn order:

"Attack Declared" Ace, I respond with "Block Declared" Tidus, Seven's effect stops my ability to block with Tidus, I play Leviathan to remove Seven from the field.

Now here is a break down of the play:

Ace "Attack" > Tidus "Block" > Seven "Ability" > Leviathan targets Seven

So the rules say to resolve the conflict in reverse order of the play, here is the break down

Leviathan targets Seven (Seven returns to owners hand) > Seven's "Ability" is null due to not being on the field > Tidus "Blocks" > Ace is "Destroyed"

I have been reading forums and I have been getting conflicting information, such as "Abilities" are not removed when the card that puts them into effect is removed unless the countering card says specifically "Cancel". 

Let me know what you think and if I could get an official ruling that would be great!


-imest