Cubey, MAN, you are fishing, without bait.
Nice try on all fronts but every argument is baseless.
1) Flexible cords CANNOT be run through walls. Regardless of what you think you found you did not find any exemption for this rule. Mainly because there is none.
2) Your "RV cord through a hatch theory" is totally WRONG. This is NOT a cord through a wall. It is a cord through a SPECIFICALLY designed hatch with a notch for the cord.
Over the many years of coming to boards like this has taught me a few things. One of those things is recognizing when someone makes a statement like "Anyone can make a statement that something is dangerous but without the explaination as to why it is dangerous, how would anyone understand and not do it? Tell me WHY and WHERE it is dangerous.". This is almost always an indication that someone is fishing for the answer they want to hear. If they don't get that answer they call foul because they didn't get a full and detailed explanation. Sometimes a full and detailed explanation is quick and easy to put into words. Sometimes a full and detailed explanation is not worth it. Sometimes it can be well over the head of the average lay person.
Sometimes folks just need to be told "DON'T DO IT", "THIS IS DANGEROUS", and they need to simply accept that.
It's not like we are making out on this stuff. It's not like by telling you this our brother-in-law who is an electrician as well is going to get the job.
We say this stuff because we know better, not because we will gain anything from it.
This is why it amazes me when folks question us up and down the block when we say not to do certain things. Sometimes code is just CODE!