The right to silence in Ireland derives from both common law and from our constitution. It is not a trivial matter.
Similarly, the presumption of innocence is not a novel, abstract, or symbolic idea - in jurisprudence it is actually considered a piece of evidence before the courts. There is a good reason that the "golden thread" is one of the first things learned by law students, and why presumption of innocence is included in the Universal Declaration of Human Rights and countless other international and national codes.
There are limited and prescribed circumstances where a presumption of guilt can be applied but they are few and far between, particularly in common law countries. Legal history shows a strong correlation between presumption of guilt and kangaroos courts. "Give me the man and I will give you the case against him", etc.
We have so many examples of how various organs of the state fail to meet basic standards of competence and conduct: penalty points scandal, bogus breathalysers, Kerry babies, GUBU, voting machines, Rent Pressure Zones, Slaintecare, the Children's Hospital...
I would be extremely uneasy at giving them anything that weakens my rights and due process.