State’s witness, the Grand Vizier and the Grand Vizier

Good night!
I read an article by the rabbi in which you attacked a judge who claimed that according to the Torah, a state witness is not valid because he is touching, and you argued that if it is invalid as a relative, then the state is not acting according to the law, and if it is out of fear of lying, then the prosecutor’s office is certainly conducting investigations to verify this.
I think his words can be explained as follows: that it is true that there are means to investigate the testimony, but the Torah, even in cases where the objection is a fear of lying, does not allow for investigating the testimony and thereby establishing his testimony.
And this is because the Torah taught that a person who is touched, even if there is room to extract truth from his words, still has no witness. And this is because the Torah revealed that it is not possible to know where the interest and the lie are (and compare it to the well-known words of the Chazo”a about bribery).
In another wording: According to the MMA, if there is a suspicion that it is false, then it is not a witness, and if there is a way to present the testimony, then it is just an estimate that the courts do not rule on, and not testimony. (And only the NPA if it is invalid in testimony as a suspicion of falsehood or invalid in the name of a witness as a relative, this concerns testimony that is idle)
And this perhaps fits with the words of the Rabbinate that a witness gives power to the judge (unlike prohibitions, in which there is no principled obligation to his words, but only to trust), and in any case, a witness who has a fear that a lie cannot bind the judge, and therefore does not have the name “witness.”
And interestingly enough, I find it difficult: How do the words of the Gerashsh fit in with the famous definition of the Ezrachi Rabbi, that it is not simply that the witnesses are only trusted, but rather that they see the story through them, and in his words, “witnesses are the spectacles of the witnesses” (and indeed the Avanz defined something similar in his explanation of the witness who becomes a judge)?
thanks