You are correct, every situation is different and that is why the general advice is to discard tyres after 5 years, irrespective of usage.
If you feel that your storage and usage is not contributing to tyre decay over that period nobody can and will prevent you from using these tyres after 5 years and nobody really can identify and define an internal compound – decay.
However keep in mind that in case of accidents or even fatalities insurance companies will not entertain your claim which might become ruinous for you in case of fatalities or even put you in a wheelchair.
In the final analysis: The choice is yours alone…..