So if you're rich and have the time there may be consequences, but ultimately since anyone can file a false DMCA notice, there's really no assurance that you will ever get your own lawyer's fees back let alone damages (even if they were awarded).

Perjury is a pretty terrible mechanism, frankly. The whole law was and is poorly conceived.

I'm not so sure. It's a fact that he was involved in the development of this new feature, and it's his opinion that he originated the idea. Whether he did or not is for a court to decide, but he's not committing perjury by believing this.

Now if he knows he didn't originate the idea and has brought vexatious proceedings, then sure, this may be perjury, but we are some way off knowing this, and i don't think we'll be in a position to determine this either way.

Ideas aren't copyrightable. If they're not using his code or art or actual copyrightable materials, then there is no copyright infringement.

He wasn't involved, from all accounts.

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.

To file a DMCA complaint you must be the copyright holder, or authorized to act on their behalf.

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.

So, if they aren't the copyright holder (as in this case) they have committed perjury by asserting they are.

Possibly not if they thought they had a valid claim, but I really don't know how that would work out in practice.