My hanwags have taken a beaten over the last 5 yrs, this yr alone they have seen over 200 mountain Km's with heavy packs and not one issue with them. Think they would do something for you.
I think it needs to be noted that the original poster never disputed Hanwag's position that boots stored for several years can degrade due to hydrolysis. I think it is likely that the "brand new" boots when returned to Hanwag turned out to be older than a couple of months and perhaps that is why their position on the warranty changed. The original poster hasn't returned to the forum since then (Nov 2017 ) there is limited information to go on.
Rubber soled boots have a shelf life, not unlike the tires on your truck. Eventually they are going to break down on you and need to be replaced even if they have zero miles on them. I've had Lowa, Meindl, Salomon and many other boots suffer from the effects of hydrolysis and fail on me. I've yet to have a pair of Hanwag's fail on me and I have owned close to 10 pairs, but the soles on them are certainly not exempt from hydrolysis and I will not be surprised if it happens at some point.
You can mitigate the Hydrolysis by proper storage, maintenance and use. Store boots in a dry and ventilated area. Storing them in the box is one of the worst things you can do. Lack of use is another factor. Boots that are use more frequently are said to be less susceptible to hydrolysis. Maintenance is another major factor. Properly cleaning your boots especially when used in wet & muddy conditions will help prolong their life.
I'm certainly not saying that Hanwag handled this situation in best possible way according to the OP story but we really don't know the complete facts. I do think it is unrealistic to expect any boot maker to provide much in the way of a warranty for hydrolysis due to age and storage issues.