I would think very carefully about drawing such conclusions...
This thread shines a little light on a couple of the generally preached tenets about TP:
"TP doesn't decompose when it's buried - you have to pack it out, burn it, etc." It's only one study, but this data set indicates that that's just wrong. Anyone have any data that supports that TP does not decompose?
I'm not aware of anyone who made such a claim. I suspect that most knowledgeable people believe that buried TP will decompose in a moist temperate environment. (Its primary constituent is cellulose--the same as many plants.) However, it will probably last much longer in a dry or below freezing environment.
"Animals will dig up the TP." Apparently, there's no data to support that, either.
Is there any data to suggest that animals will not dig it up? What if you use scented TP? Perhaps animals will dig up feces too, but it is less noticeable than TP. Or perhaps digging up TP is just a side effect of digging up feces. Or perhaps only some animals will dig it up.
Disclaimer - it appears that there is very little data around any of this. It probably needs several good validated studies before anyone should really push any conclusions.
Given that there is very little data, the correct conclusion is "insufficient data--no conclusion" not a bunch of unsupported conclusions.
There is also the problem of observational bias--if you look for something you are more likely to find it. (Conversely, if you don't look for something you are less likely to find it.) Designing good unbiased experiments can be difficult.
Guthook's friend's experiments look like a good start* (although they need to be tried elsewhere and under different conditions). FWIW, septic tank safe/marine/fast dissolving/RV TP is designed to degrade rapidly--thus it is not surprising that it degraded faster than the "standard" TPs tested.
* Note that most of the experiment period was dry with significant rain only occurring near the end of the test period.
I suspect the answers are likely to be highly dependent on the environment: eg: temp range? (frozen?), moisture levels? (desert?), soil type?
The hiking "authorities" (official or self-proclaimed) often try to give advice that is as broad as possible. So the reason for some advised procedure might apply to some set of conditions but not another. And they may also tend to prefer "safe" options such as carrying out TP is always environmentally safe compared to leaving it. There is also the issue of usage level--a practice that might be acceptable in lightly used areas might be unacceptable in heavily used areas.
Doug