The operative word in your statement is “should”, not “must”. And, exceptions can be made. However, if your pastor is requiring she go through RCIA, then follow his dictate.
The Catechesis provided by RCIA is a good thing. There are many “cradle” Catholics who are woefully uncatechised, thinking if they were born into the faith, they understand it.
And, don’t go running to the Bishop because you don’t like the decision of your pastor. Instead, talk to the pastor, and if he is unwilling to change his mind, only after your discussion, consider going to the Bishop.
If the Bishop had to intervene for people who don’t agree with the decisions of their pastors, he would have not time for his ecclesiastical duties and might as well be acting pastor at all his perishes.
Pax et Bonum!