From my reading of the definition in Vatican I the ex-cathedra is very clear so no sham there:
**"we teach and define as a divinely revealed dogma that
when the Roman pontiff speaks EX CATHEDRA,
that is, when, in the exercise of his office as shepherd and teacher of all Christians, in virtue of his supreme apostolic authority,
he defines a doctrine concerning faith or morals to be held by the whole church, he possesses, by the divine assistance promised to him in blessed Peter, that infallibility which the divine Redeemer willed his church to enjoy in defining doctrine concerning faith or morals.
Therefore, such definitions of the Roman pontiff are of themselves, and not by the consent of the church, irreformable.
So then, should anyone, which God forbid, have the temerity to reject this definition of ours: let him be anathema."**
This is a classic way of ex-cathedra saying " teach and define" with “anathema” at the end. All such statements made by the Pope whether in a bull, encyclical, or council are infallable. The document is not as important as how the stament is pronounced.
The problem starts with claiming the ordinary mag. is infallable.
If you read closly the word UNIVERSAL is used in Vatican I to clearify when the ordinary magisterium is infallable. UNIVERSAL in this case means always and everywhere:
"Wherefore, by divine and catholic faith all those things are to be believed which are contained in the word of God as found in scripture and tradition, and which are proposed by the church as matters to be believed as divinely revealed, whether by her solemn judgment or in her ordinary and universal magisterium."
So when a pope bishop or layman for that matter Echo (catechise) the universally held teaching of the Church then they are infallable too.