If a holder disclaims a power of appointment or other power not held in a fiduciary capacity, the following rules apply:
A. If the holder has not exercised the power, the disclaimer takes effect as of the time the instrument creating the power becomes irrevocable.
B. If the holder has exercised the power and the disclaimer is of a power other than a presently exercisable general power of appointment, the disclaimer takes effect immediately after the last exercise of the power.
C. The instrument creating the power is construed as if the power expired when the disclaimer became effective.