What about the woman dusting for Fingerprints?
Did she find any of her own fingerprints? No. Did the method obliterate any others or contaminate the scene? No.
So by hook or by crook, either in spec or out, her method and / or use of gloves is immaterial.
Would I be upset if it were my child they were looking for? Absofrickilutely, and it looks like Gerry was in the habit of wearing more pairs of nitrile gloves than fingerprint lady, ironically enough.
I get that the parents were building this 'incompetent coppers' angle - and I'm sure some of it might be warranted (as much as unwarranted in all likelihood), but in this instance it's an irrelevance. You can try to make the quantum leap from 'fingerprint lady doesn't follow protocol' to 'what an absolute load of inept halfwits' if you insist, but it starts to look a lot like desperate revisionism. Even a staunch supporter must see the level of rigour in the fingerprint analysis.