What debris? If you had a roof redone and you had stuff in the attic that you were concerned about, it would have been wise to cover with plastic prior to starting the job.
Leveraging your obligation to the roofer that did your job isn't really a correct response to this minor situation, and I'm not the judge in a court of law, but if you fail to pay the roofer over a little bit of debris in the attic, you'll get a lien on your property and pay their lawyers costs.
Billy's comments are flat wrong, it is clear he isn't holding your purse.
If you had concerns before the work began, it should have been addressed at that time. If you didn't realize it would have happened, if you used Home Depot At Home Services, call the PM and they WILL help. If you used any other roofing company, get your broom, they aren't responsible for anything besides a good roof on your house, especially not a little bit of junk that fell down. If they did a total redecking and it was a major job, they might be willing to come out, call them.
Frankly, it doesn't sound like a big mess, but I haven't seen it.