Well obviously their contention is that you're buying a license to use the software and not the software itself. You're free to disagree but it's internally consistent.
They can disagree all they want, but it is on them to prove that I agreed to buy a license, when I am physically holding something I bought. I didn't have to sign a contract for it. Adding terms after the purchase makes it a post-purchase agreement and that is unenforceable in most western jurisdictions.
Anyway, as I replied to the other guy, Venor v. Autodesk shows that some courts have upheld "shrinkwrap" licensing. I don't think it's a settled question in US law.
That may be their contention, but this is exactly why this is fundamentally different to the copyleft case. The GPL requires none of this.
I would add that it seems pretty specious to argue that I bought a license when the license was not presented to me at the time I paid for the product and left the store, but I accept that this could be their contention.