I wondered about the chown thing myself, but ended up concluding that the author was misremembering the errors. He probably saw some chown messages and didn't read all the hundreds of lines (I certainly don't read every line of hundreds of log lines, I skim looking for key words), meaning many of them could well have been rm failures that he misremembered as chown. But whatever it was doing, the author would have been wise to read it before deleting the directory it contained, as it would have saved him a lot of trouble finding all the bits and pieces he had to hunt down later.