A properly designed spring shouldn't have a problem. But I think that article is still pretty oversimplified. Bad design, bad material, bad manufacturing, you still could have a problem. Creep and fatigue is not the only failure mode of steel. You can also have stress corrosion cracking (esp. a problem in some stainless steels) plus others.
Without knowing the exact designer stress amounts, material limits, etc., we'll never know for sure. Even then material science is all about averages and statistics. No two steel batches are ever EXACTLY alike. Add the variances in manufacturing the part, heat treatments, treatment after manufacturing, etc. there are lots of variables for any individual piece of metal.
There are cases where mags are stored full for decades and still function fine. If you are at all worried, I'd just load the mag full and then take one out just to be safe if you like. If the spring even does weaken a little while fully loaded, it most likely will fail on the last round or two. Time for a new mag anyway!