Zindello's page

While the wording is unfortunate, it seems pretty clear that the intended use of round in the "Making an AoO" section is this one:

Combat wrote:

When the rules refer to a “full round”, they usually mean a span of time from a particular initiative count in one round to the same initiative count

...

This.

There isn't a 'universal round' where all characters take their turn and then the round resets.

Every character has their own personal round that begins and ends on their place in the initiative.

That's the view closest to making sense that I've seen on it; you get your attacks without the penalty, then declare you're fighting defensively (if you haven't used your swift by then, which you probably have anyway), get the AC bonus, and just take the penalty on your AoOs (and Opportune Parry).

It's this.

Basically, swashbucklers get the flexibility to full round attack then use their swift action to gain the bonuses/penalties from fighting defensively til the start of your next turn.

Then get yourself a weapon with Answering on it and that -2 becomes negligible. ;)