From the news articles I get the impression that it wasn't merely the 60 seconds of silence which posed the problem, but that the composer tongue-in-cheekedly attributed John Cage as co-composer. In so doing, he openly admitted that his inspiration for the "piece" was Mr. Cage's own work. I don't think the issue was the silence as much as it was using Cage's name without permission. Had he approached the Cage estate ahead of time, he would have probably been given permission to use the name for a reasonable donation to whatever work that estate does.