You fail to understand how eastern canon law works, this is your problem.

1- in the east canon law is not something obligatory like in the Latin Church.
Canon law is something applied by a priest in the way a Dr. applies medicine, not all canons are actually followed. They're only applied by a priest when he is dealing one on one with a layperson, the priest may tell one that they can go to a Greek Orthodox liturgy and tell someone else not to. We simply do not look at a list of laws and self apply. We are not the Dr's of ourselves.

Canons are looked at by bishops and priests as a rudder to steer by not as some rule or regulation, they're ignored frequently.

Two Churches take canons according to the letter, Rome and the Russian (Greek) Orthodox, largely because Latins tend to legalism and the Russians need the canons to (in their mind) justify their schism.

The point you are missing is that the obligation is on you to prove your own assertion.  Despite numerous posts on this, you have not shown that any proof that eastern Catholics were permitted to go to schismatic liturgies prior to V2.  

The reception of sacraments privately for the dying is not the same as actively participating in a schismatic liturgy which is being done publicly,and if a catholic attends, he scandalously gives approval to a liturgy that is outside of the Church.  

the fact that the holy office consistently issued decrees indicates that people were attending said liturgies otherwise there would be no need.
Franciscan and Jesuit clerics had to report to the Orthodox bishops in the holy land, hope that doesn't make your head explode.

you are extremely dense. How can I produce a canon from pre 1990? 
no canons exist in the east for me to show you and the current code was worked on for over 120 years and is not authoritative if particular churches have their own laws. No one on the face of the earth can prove a negative, 
I can prove someone is Hitler's shoeshine boy.
I can not prove he's virtuous.
I also can never prove that Latin canons using Latin terminology exist where none exist.
The very passage you quote from the encyclopedia is in error.
Armenia was never part of the Roman Empire and only sent delegations to the first three councils. 
They never separated from Rome and to this day have never to my knowledge denied the the claims of Rome and to this day commune Roman Catholics.
In what way are they or when did they separate themselves from Rome?
Is it hard to exercise your canon law degree?
When were you ordained and put in charge of declaring who is schematic?
Is this something women do in traditional circles?

Mods change my name to Hitler's shoeshine boy.

I don't think there's anything inherently wrong with switching Rites or deciding to go to Eastern Rite masses when you convert, but I'd heed what Matthew and Ladislaus said and be sure to not just pick it for the sake of it being exotic or having more interesting "smells and bells". If you feel like the Eastern Rite is preferable for you, then go ahead. But don't pick it because you think it looks prettier.

My friend Carlos went to a terrible seminary in Washington D.C. and the professors spewing heresy caused him to lose his Faith. He later switched to the Byzantine Rite. At the time, he had no idea that he couldn't just switch back to the Roman Rite. Although, depending where you are, the Byzantine priests are most likely fully Conciliarized. Like Matthew said, this crisis is much more than a fight for the Mass.