In Canon 96 "insofar as they are in ecclesiastical communion" is absolutely clear. An exception is explictly given to someone who has willingly left ecclesiastical communion by all conventions of canonical interpretation.
This does not contradict Canon 96 which clearly provides for someone has willfully left ecclesiastical communion to be excepted. No one is held against their free will to belong to a Church they wish to leave nor to the legislation of that Church. While we hope to eventually be in full ecclesial and Eucharistic communion with the Orthodox, the fact remains that we are still ecclesiastically separated. The renunciation of the anathemas of 1054 is a start, but we are most certainly not yet in* full ecclesiastical communion.* Canon 11 is never interpreted as binding or contradicting someone who has left ecclesiastical communion consistent with Canon 96.
I’m not sure what the obsession is with the catechumenate, but it is irrelelvant for someone who has left ecclesiastical communion consistent with Canon 96.
The law does expressly provide otherwise, namely in Canon 96, and that is very clearly stated. I see nothing compelling in what you’ve stated to change any of the normal conventions of interpretation of the relation between Canons 96 and 112, but rather to confirm the norms of interpretation. When a Catholic wilfully leaves the Church of their own free will to become Orthodox, they have left ecclesiastical communion and Canon 96 most definitely applies. Law is only applicable when there is a person to be a subject of the law. The law clearly does not bind one who wishes to be no longer bound by leaving ecclesiastical communion.
The commentary clearly states “those baptised in the separated and reformed churches”. Catholics are not in that class, even if they commit heresy, schism, or apostacy. One can not formally leave the Catholic Church after baptism, not spiritually as the mark of baptism (faith and hope) remains, even without charity.
But that person without charity is not saved:
CCC 837 “Fully incorporated into the society of the Church are those who, possessing the Spirit of Christ, accept all the means of salvation given to the Church together with her entire organization, and those who – by the bonds constituted by the profession of faith, the sacraments, ecclesiastical government, and communion – are joined in the visible structure of the Church of Christ, who rules her through the Supreme Pontiff and the bishops. Even though incorporated into the Church, one who does not however persevere in charity is not saved. He remains indeed in the bosom of the Church, but “in body” not “in heart.”