I think this has been covered before and it's pretty common w/ sleds. It takes awhile to list out all of the parts, etc. In most cases, sleds are totalled b/c of the high cost of parts and hours to repair- just not worth it. In that case, they get no work. So at least recoup their time spent providing that.
That being said, I agree that basement estimates, painters, etc- most usually don't charge. But that's b/c there is competition out there. Most advertise free estimates as a way to get in the door. And then hopefully, they land the work. Same for cars- in most cases, your car isn't totalled, so they want to provide a free estiamte, hoping you'll have the work done there.
Sleds are just generally totalled so they have to get something. Can't fault the business owner. If they were up front about it, then they weren't trying to be shady. The good news is, your insurance should cover this in their portion- it shouldn't be a totally separate, out of pocket thing for you.
Either way- no fun if you needed a repair estimate. Hope your ride is back to normal soon.