Low blow for sure, but par for the course. However, this is a lesson for any business out there to carefully vet their clients on a continual basis...
If there's any hint of financial trouble, stop dealing with them. Or, alternatively, cash on delivery or payment through a factor. Don't wait until BK rumors are being widely published in the news media, because sometimes that's too late. Know your clients.
Bottom line is clawbacks are nothing new. Another arcane detail of bankruptcy law most aren't aware of. Shame so many businesses are getting burned again.