I don't have the answer to your legal question, but if your router supports it, you might consider putting rate limits on the machines IP so they are slowed to

I don't have the answer to your legal question, but if your router supports it, you might consider putting rate limits on the machines IP so they are slowed to a crawl. Maybe 10kb/s. Enough to make it think it is working but not enough to upload all the things. This assumes your appliance will still work as designed when their spooler/buffer is full. Or another trick is to drop any packets above 600 bytes. Most API calls will work but data transfers won't unless their device is clever.