ASUS develops and maintains of the low level software, not Google. Google only provides the Android OS and some creative input. This explains the delays, as Taiwanese companies are notorious for poor software support.
As you alluded to, the issues MAY be some kind of interference. With enough investigation, this can be mitigated through software. I work for a company that manufactures devices with 3rd party hardware very similar to the Nexus 7, and you'd be surprised how much errata we get for botched IC's that we then have to code around. Almost anything can be mitigated with software.
Either way, I highly doubt it has anything to do with charging. That link you provided talks about capacitive coupling from the switching transformer inside the power supply, how could this cause issues when the device isn't being charged?
In saying that, you have to remember that the number of users with actual issues is VERY small. Forget about threads on here for statistics, as this is where people come to moan about it.
Like I said, my touchscreen issues are clearly software related as it was flawless before the latest update JSS15R.