Nifft said:
Fair enough. But if you get to make arbitrary "apparent exceptions" to excuse clear rules violations, then so do we...
Another example recently is the Haste spell.
The text for Dodge bonuses states that no spell provides a Dodge bonus. The text for Haste states that the Haste spell provides a Dodge bonus.
The general principle is that more specific takes precedence over less specific - the rule for the Haste spell trumps the rule for all spells.
This is similar - we have a rule that all special abilities are Ex, Su, or Sp, and then we have the Pincer Staff - a special attack that is not Ex, Su, or Sp. The rule for the Pincer Staff special ability overrides the rule for all special abilities.
When I say 'apparent exception', I mean it's an exception that's apparent. We can see that it's an exception, because it conflicts with a more general rule.
Your exception is arbitrary, rather than apparent - Spells is listed as a special attack, but you're saying it's an exception to the rule that Ability Focus applies to special attacks because another feat exists that applies to spells. Spell Focus doesn't by its existence exclude the possibility of Ability Focus applying to spells, so the exception is not derived from anything written... it's an arbitrary preference thing.
-Hyp.