@Chris why sue Autocad

IANAL, but the reason he sued Autocad was under tort law for interfering with his business.

Here is a person who makes his living by buying and selling things on eBay. Note that he's not the first person to do this.

So his claim is that Autocad's complaints caused him harm because he lost access to his eBay account.

His case has merit, meaning that the complaint is strong enough to go to trial. It doesn't mean he is going to win.

I'm also not sure that Autocad did the smartest thing by using the DCMA to stop the auction.

Without seeing the actual shrink wrap contract, its hard to say.