D: All of the above! They'll all do the job. I think letting his boy play with it and relic however he did, would give the most mojo (echh) of any method, even over the owner playing it for years of natural wear!
To relic a guitar is to have owned it for thirty or fourty years, and to have played it just about every day of those years.
And to remember and regret every bang or thump or rub that it suffered.
Any wannabee can buy sandpaper and imagine that the damage they are doing is realistic.
Please, don't show that picture to my little ones. They already find the amps and guitars nearly irresistible sources of amusement. If you add a hammer to the mix I can only image the carnage.
Relic job made simple: Obtain guitar new in 1964, play it (off and on) for 44 years, done. That is what I did before giving it to my son who is the proud owner of a made-in-Kalamazoo Epiphone relic.