I honestly doubt any severe repercussions will occur, the DMCA is too weasel worded. Defamation is another matter. Accusing a company like Atlassian of hosting pirated porn is a serious commercial matter. (Slandering open source developers is another matter, freedom of speech and all that, America hasn't really grasped the concept of reasonableness and balance.)
Accusations that are clearly defamatory against a commercial entity can harm political donations, jobs in battleground states, and inflict restraint of trade, on the long run-up to a major and likely to be bitter election... That is clearly not going to fly with elected judges and elected political representatives.
The question is whether legitimate businesses involved in legitimate trade will simply ignore the action or file for defamation. Winning or losing doesn't matter, most of the porn companies are probably small enough that bad publicity and legal fees will cripple them. Obviously winning (even if by default) would be better, it would create case law on the issue.
The problem with DMCA is that we've been here before many times. And there have been DMCA cases the industry has lost. Yet nothing has changed, no precedents have been set, no behaviour on the part of industry or takedown farms has been modified. You'll have to do something new.