But see, that's the same boat we were in before we had the DMCA. It's a problem that there's a two-week blackout on your stuff if someone files a takedown notic

But see, that's the same boat we were in before we had the DMCA. It's a problem that there's a two-week blackout on your stuff if someone files a takedown notice, but it does protect you from being sued right off the bat. In other words, if he's unwilling to risk filing the counter-notice, then without the DMCA, he wouldn't (or shouldn't) have been willing to risk uploading the models at all. But to answer your rhetorical question, if they do sue, you contact groups like the EFF and ask for help. (Better yet, contact them before filing the counter-notification). They would likely be happy to work to establish a good precedent in a novel situation like this.