Dammit, possibly missed something (arcane mastery)

[Boci]

I never noticed this before but the feat arcane mastery that lets you take a 10 on a caster level check references taking a 10 on a skill. The exact wording is “as if the caster level check was a skill check”. Does this mean you cannot use the feat if you are rushed or threatened?

[tyckspoon]

C. Arc errata adds (you can do this even if threatened) to the feat.