Its a difficult one to judge this, because its not obvious how many times the launch control has been used, and exactly what wording is written about the use and warranty implictaions, of its use, in the owners handbook.

If he's been using it 10 times a day, every day since hes had it, he's gotta "reasonably" expect that somethings gotta give sooner or later?

If hes used it once and its caused damage, thats slightly different.

Any reasonable person wouldnt expect to abuse something and it to never ever break?

Surely nissan can interrogate the ecu and establish a pattern of use etc etc? Perhaps they have, hence the refusal to repair?