I doubt you'll get an answer to that question any time soon.
I suspect westom doesn't know the difference between insulation breakdown leakage and the reactive leakage you see from the 47nF caps typically used in the EMI filtering circuit of ATX PSUs.
If the leakage is due to failing insulation, that *is* a serious issue which does need to be investigated and put right. Reactive leakage due to EMI filtering otoh, is an altogether different kettle of fish notwithstanding that enough PCs hooked up to a circuit where the CPC wire has gone open circuit can present a human safety hazard (but one would hope that someone would start to question the tingling sensation they get every time they make contact with the case of the PC(s) in question).
One thing to consider with a single *un-earthed* PC is that the leakage source is effectively a 120v supply with a leading reactive impedance of 33.863K ohms (voltage divider effect of a pair of 47nF caps in series across a 240v supply with, effectively, a parallel connection to a very low impedance 240v 50Hz ac supply).
Even the combined effect of ten such unearthed PCs is unlikely to pose an electrocution hazard. It's the peripheral connections that are likely to draw attention to a missing CPC on a UK ring main and a call to an electrician to solve the mystery of why so many devices are getting fried whenever they're plugged in or disconnected from the PC (both the peripherals and the interfaces concerned).
Westom may well specialise in the design of equipment that calls for such low leakage requirements (medical or specialist research equipment springs to mind) but if this is the case, then he's specialised his knowledge to just this subset, an extremely narrow field indeed. Consequently, he's no longer qualified to comment on the wider field of leakage currents from general every day kit without the benefit of a refresher course in "Leakage 101".
Such specialisation to that extreme is very worrying. One such example that comes to my mind is the case of all those early PCI based sound cards (and the PCI based on-board sound chips) that started to appear around the turn of the century which all, to a chip, clipped the line (and CD analogue audio) inputs at -2dB FSD due to the sound card and MoBo manufacturers blindly following the reference design offered by the sound chips makers where the -6dB sensitivity option had been hardwired to reduce the noise floor.
Basically, this was achieved by doubling the reference voltage for the ADC but forgetting the need to double the line input buffer amp supply rail voltage to raise the already marginal clipping level that was otherwise sufficient when the more sensitive setting had been chosen.
I think it took a good (well, bad really) 5 or more years before the penny finally dropped and the problem was properly addressed. You had to be overly focussed (specialised) in the digital aspect and totally ignorant of the fundamentals of audio circuitry design to miss that particular "Schoolboy Howler" of design incompetence to make that mistake (and worse still, perpetrate it for so damned long!).
Johnny B Good
Johnny B Good