All nuts or anything with a thread is in tensile load, this is how the thread maintains its grip on the mating threaded part.
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Torque settings are there to maintain the fixing in the "elastic region" of the material a bit like a bungy cord, if you pull it too tight it will fail eventually, if you simply apply a reasonable amount of stretch to the bungy cord it will last you for 20 years or more.
The bolt is no different, the length of time to failure may be, but who knows how long that will be ?
You will get no argument from me on how nuts and bolts work. However, the only load on these fasteners is what is applied during initial installation. As for the bolt/nut stretching continuously over the years... no. Without additional load applied the material is not going to plastically deform. A bungy cord is made of biodegradable material and is not a good analogy for the bolt/nut over time.
In this particular installation the bolt is subjected to lateral shear and the nut's job is to keep the bolt from falling out.
As I said several times in this thread (and Wil_h is right... it's all been said multiple times in this thread) use the high-strength fasteners if you want to, it will not hurt anything.
