Ridiculous. Canonizations are not infallible in the same way that Trent is, or the dogma of the Assumption is.
You are correct in your starement, but not in the way that you intend
No doctrine of the Church is "infallible". Doctrines can be dogmatic, common teaching, opinions or hold a number of other thelogical marks within the spectrum of theological weights.
Infallibility is a property of the Magisterium, not the content of the Deposit of Faith.
The theological canons of Trent have been taught infallibly by the Extraordinary Magisterium of the Body of Bishop gathered in General Council.
The Assumption has been taught infallibly by an exercise of the Extraordinary Magisterium personal to the Bishop of Rome.
Canonisations are infallible exercises of the Ordinary Magisterium exercised by the Bishop of Rome.
See! None of these are infallible in the same way.
Most dissenters from papal infallibility (Protestants, Orthodox, Old Catholics) are grossly mistaken about that from which they are dissenting. They confuse the power of the Magisterium to teach infallibly with the power of the Magisterium to teach dogmatically. When most deny papal infallibility, what they really mean is that they deny the power of the personal papal Magisterium to teach dogmatically. That same confusion is surfacing here.