“We had already pointed out to your client that our client is entitled to claims for damages in accordance with Section 97a (4) UrhG in the event of an unjustified claim,” writes the lawyers acting on behalf of LAION.
OK, so they're legally entitled to throw this back into the faces of whoever makes these kind of requests.
Still - it does seem rather petty. Common sense (and basic decency) would tell us to take a less knee-jerk approach. A simple form letter (explaining the lack of legal merit to their claim) should suffice to quell at least 80 percent of these claims. If the claimant persists, then yeah, you could thrown down the gauntlet like this.
Otherwise, it comes off as rather haughty and aggressive (and as the Germans would say, zickig) to breathe acid at (apparently simply uninformed) claimants like these.