إن العزم على الوطء عذر في باب الظهار؛ لأنه كالوجود
In the chapter on zihar, a firm intention to have intercourse is treated as relevant to a particular legal consequence, being considered in that respect as though the act occurred.
Here azm does not mean a passing wish. A firm resolve may have a specified effect where the relevant legal rule establishes one. That does not mean intention is equivalent to external action in every legal setting.
The example illustrates the strength implied in the word; the principal discussion then concerns azimah as an original legal ruling and rukhsah as an exceptional concession.