Uh-oh, today's HN reader would be looking for a way to pirate that work so they could view any time they want.
More seriously, were they wanting to keep it hidden because they weren't sure it was good enough? A bit of self-conciousness on how my stick figures are a lot less realistic than Bob's paintings in his cave? Were they afraid of the poparazzi effect of everyone wanting their autograph for being the rockstar painter of their day? Or are we just congecturing too much about wanting to keep them hidden? More questions than answers.