Thomson are just saying things to cover their arses from people who don't put things together properly and, instead of those people just admitting that fact, they will go to court with some science that most absolutely most definitely was the cause of the failure.
You hear cries of, "but i always use a torque wrench" from others yet how many of those people ever calibrate the wrenches?. Do they honestly think that the wrench is definitely right and remains so for ever more?. Do they always wind off the torque setting after using the wrench and store them slack?. The majority of home and bike/car mechanics do none of this and alot of wrenches are way off.
What alot of people dont get is that down at low figures a teeny bit out is massive, as a percentage, compared to the same error at car wheel nut levels, for example. The errors can vary alot within the whole range of the wrench, too. It really depends on the quality, storage conditions, and how the wrench has been used if it is second hand.
It so much less hassle to have some small print, to cover an outside possibility, and take the hit of a very small percentage of people getting scared off a product.
If you really think these are sure death products then ask them to provide details of what lab tests they have done, the testing protocol(temp ranges, number of cycles, number of failures etc) and the total number of items tested. Also; do they spot test, batch test, test each new supply of billet etc and ask for the results of the tests.
Everything mechanical has a point where it will fail. What is important is knowing how it might fail and how many out of large number will fail under certain conditions. Then the consumer can make the right call if concerned.