From reading the opinion, I think the argument goes something like this:
> First, LinkedIn does not contest hiQ’s evidence that contracts exist between hiQ and some customers, including eBay, Capital One, and GoDaddy
> Second, hiQ will likely be able to establish that LinkedIn knew of hiQ’s scraping activity and products for some time. LinkedIn began sending representatives to hiQ’s Elevate conferences in October 2015
> Third, LinkedIn’s threats to invoke the CFAA and implementation of technical measures selectively to ban hiQ bots could well constitute “intentional acts designed to induce a breach or disruption” of hiQ’s contractual relationships with third parties.
> Fourth, the contractual relationships between hiQ and third parties have been disrupted and “now hang[] in the balance.” Without access to LinkedIn data, hiQ will likely be unable to deliver its services to its existing customers as promised.
> Last, hiQ is harmed by the disruption to its existing contracts and interference with its pending contracts. Without the revenue from sale of its products, hiQ will likely go out of business.
> LinkedIn does not specifically challenge hiQ’s ability to make out any of these elements of a tortious interference claim. Instead, LinkedIn maintains that it has a “legitimate business purpose” defense to any such claim. ... That contention is an affirmative justification defense for which LinkedIn bears the burden of proof.
So the real situation is that you can't go out and start blocking access you knew about in a way that would interfer with third party contracts without a legitimate business reason to do so. The burden of proving the legitimacy of that business reason is on you.
edit:
TLDR;
> "A party may not ... under the guise of competition ... induce the breach of a competitor’s contract in order to secure an economic advantage."