
Apologies if I appear to be stirring the pot, but...
This is actually a legitimate point which can be extended to other types of boots. Ie, there is a gradient of boots from those that offer virtually (or actually) no ankle support to those that clearly do (eg, it is virtually impossible to injure your ankle while wearing down-hill ski boots due to the excellent ankle support that they definitely do provide). Therefore any data that shows that there is no ankle support from boots is clearly not taking down-hill ski boots into consideration, and therefore clearly does not include the entire gradient of boots in the study that was used and therefore the results cannot be expected to apply all brands and models of bushwalking boots that were not used in the test. In fact it cannot even apply to brands/models that were used in the tests if they are worn/laced/used differently, or for different activities.
All that can be determined from such data is that the particular brand/model(s) of boots that they used for testing, in the way they were worn, and doing the controlled activities that they did, they did not appear to prevent ankle injuries.
Note that I do wear sneakers bushwalking occasionally and I even go bare feet on some bushwalks. So I'm not a boots-are-always-better believer.
(No, I don't really think you should walk in down-hill ski boots when bushwalking.)