It was not the polices job to scrutinise and pass judgement on forensic evidence. Its their Job to secure the scene, collect and pass on any forensic evidence to the forensic staff at the lab.
We don't know what the police involved personally think of the silencer. With the exception of Stan Jones and Miller as they have made their views known to us on TV shows.
Stan Jones and Miller both express the view the silencer is genuine. Stan Jones comes across as a right cretin so that answers why he thinks its genuine. Miller on the other hand expresses the view that the silencer is genuine because the lab told him so.
As far as the lab is concerned, we know that they did not understand the dubious circumstances the silencer was found in, since DI Cook handed it to them under the assumption that Stan Jones had found it and thus the staff had a false pretence. We know from Mark Webster that Hayward had never seen backspatter in a silencer before. We know from Fletcher's testimony that he does not understand the subject of backspatter very well. And neither has he seen backspatter in a silencer before either. Thus the lab fooled themselves. Millers belief is based purely on circular reasoning.
There probably are members of EP that think what I think. But they wont dare express that in public would they?
"The Gish Gallop is the fallacious debate tactic of drowning your opponent in a flood of individually-weak arguments in order to prevent rebuttal of the whole argument collection without great effort. The Gish Gallop is a belt-fed version of the on the spot fallacy, as it's unreasonable for anyone to have a well-composed answer immediately available to every argument present in the Gallop. The Gish Gallop is named after creationist Duane Gish, who often abused it.
Gish Gallops are almost always performed with numerous other logical fallacies baked in. The myriad of component arguments constituting the Gallop may typically intersperse a few perfectly uncontroversial claims — the basic validity of which are intended to lend undue credence to the Gallop at large — with a devious hodgepodge of half-truths, outright lies, red herrings and straw men — which, if not rebutted as the fallacies they are, pile up into egregious problems for the refuter."