Strictly speaking, I think the only bit that's perjury would be falsely claiming to be the copyright holder (which probably applies in this case, though I suppose the argument could be made that they were just wrong, not lying), which still leaves plenty of room for falsely claiming that something infringes a copyright.
Yes, and it's only that assertion that is made under penalty of perjury, not the assertion that the targeted work actually infringes on that copyright.
