I think you have to consider the statement you quoted in the context of the MPEP section in which it is included.

MPEP Section 714.16 is entitled “Amendment after Notice of Allowance.” That entire section you quoted is talking ONLY about the Post-Allowance timeframe.

{{{ 714.16 AMENDMENT AFTER NOTICE OF ALLOWANCE . . .
. . . With the exception of a supplemental oath or declaration submitted in a reissue, a supplemental oath or declaration is not treated as an amendment under 37 CFR 1.312 }}}

I have to agree with you though – the way they say it, it’s not exactly straightforward.

Exactly as stated above.

(A) When filed in a nonprovisional application after the Notice of Allowance has been mailed.

(B) When filed in a reissue application at any point during the prosecution.

(C) When filed in a nonprovisional application after the payment of the Issue Fee.

(D) When filed in a reissue application after the Notice of Allowance has been mailed.

(E) (A) and (D).

26. ANSWER: (D) is the most correct answer. MPEP § 714.16, third paragraph, states “a supplemental reissue oath or declaration is treated as an amendment under 37 CFR 1.312 because the correction of the patent which it provides is an amendment of the patent, even though no amendment is physically entered into the specification or claim(s).” Answer (A) is incorrect because a supplemental oath or declaration is not treated as an amendment under 37 CFR 1.312 except when submitted in a reissue. See MPEP § 603.01. Answer (B) is incorrect because a supplemental oath or declaration in a reissue will be treated as an amendment under 37 CFR § 1.312 only if filed after allowance. Answer (C) is incorrect because amendments filed after the date the issue fee has been paid are no longer permitted under 37 CFR § 1.312. (E) is wrong because (A) is correct.