What he means is, your security considerations here must come from some perceived threat. What kind of threat do you forsee that requires this high level of security?
Usually when you consider security you start with a threat model, describing the scenarios you want to protect your systems from. And based on that you decide the necessary technical security measures that are relevant.
At some point this will happen with plastics too. Soo much plastic is ending up in nature, with soo much energy ready for the taking. When one fungus or bacteria mutates just right to munch on that feast of plastic, that vast energy source will ensure that organism multiplies rapidly.
And that is when plastic stops beeing useful for many of the tasks we humans use it for. If your plastic container decomposes as rapidly as a cardboard box, it will quickly become much less usefull.