Text of the law referenced: (4) Where the notification is unjustified or ineffective, the person notified may demand reimbursement of the necessary expenses incurred in respect of defending their rights, unless the person giving notification was not able to recognise at the point in time when notification was made that the notification was unjustified.

So it seems the notified party doesn't have to demand any money, but if they do so then only necessary costs can be demanded. I find it hard to believe that $1000 (or whatever) was a necessary cost. Otherwise, you could create companies that operate on the legal fringe that pretend to "serve humanity" when the real MO of your org is to profit from charging legal fees to regular people confused about the law. This is a new type of patent troll.

Addendum - to clarify my point, I am arguing that someone is almost definitely profiting handsomely from charging $1000 to send an email saying "nope, we still aren't infringing" and that "necessary costs" (as required by law) probably doesn't include such leeway for egregious profit taking. Otherwise, you create a huge moral hazard that silences dissent under threat of arbitrarily inflated legal fees. Not a German resident and not a lawyer though.