> If you combine the libertarian idea that a property owner can fully control what happens to their property along with the idea that the right to contract is absolute what happens when the entity that owns the road in front of my home says I can no longer use it unless I shop only at his stores?

Of all of the hypothetical arguments against libertarianism you might have picked, this is one of the least questionable ones.

If you buy a property today where property access might be a theoretical issue with no direct street access, the real estate agent, lawyer, or title clerk is already recommending/ensuring that explicit easement rights are added into the contract or the deal usually falls apart. Additionally, even if access isn't explicit in a contract, as far as I understand it, courts generally recognize a common-law right to access your property and have a number of doctrines available to ensure that nobody is just boxed in and trapped in a property with no recourse available to access it.