The last line was probably the most useful, speculating its use as a nondestructive imaging technique. The fly in the aging ointment is that, while they can watch the charge (or its response to the probe's induction of a charge - can't tell which is being measured without the article) fading over time, a single snapshot would have told them very little, since they would have had no information about the initial charge. They could, of course, have made a guess on the basis of experience with many controlled samples. But that kind of age guessing would be no better and perhaps less reliable then an experienced examiner's guess and is already out of play as unreliable. A sophisticated means of measuring moisture or certain volatile oils might produce the same sort of guesses. As a means of determining age, it's only the technology that's new. We've always been able, in many cases, to form an age guess that falls short of a confident opinion, and I suspect we're very often actually correct.
"Nothing has any value, unless you know you can give it up."