One way or another if it was pulled AFTER the contract was signed WB is in breach.
A cease and desist that would hold water can only come from two parties, the rights holders (WB) or the plaintiffs in the case. The plaintiffs would have no reason to send a cease and desist, let the rights be used and then tack any potential lost income on to the lawsuit. If WB sent the cease and desist then why would they then use the property at their own event?
You're just assuming the plaintiff wouldn't because it "anchors" your point. C&D is essentially a warning. The plaintiff felt he owned the rights to Ed and Lorraine Warren's story and their experiences dealing with the paranormal - aka what The Conjuring Universe was doing. Universal was a third party and their involvement was incidental. Plaintiff sends the C&D to back off and you're off the hook.
As far as a breach is concerned - A breach wouldn't occur if WB felt Universal intended to create a notably inferior product; or misrepresent the property. Another out is a mutual agreement between the 2 parties. In this case, it was an ongoing legal battle. WB is already involved in the legal suit, so using it in 2017's event is just house money at that point. Universal would have more to lose if they got involved, C&D or not, so they cut their losses and pivoted to Hive/Titans of Terror.
Wrong. The Conjuring WAS used at Horror Made Here 2017.
He never stated it wasn't. The difference is that 2017 was a smaller scale, walkthrough attraction - more akin to a showcase; whereas 2018 was WB's attempt to come to bat as actual competition. Agreements usually tend to go year to year, so when 2018 came around, WB said 'Nope".
You don't allow a good-standing partner to invest all this time, money, and resources to create a quality product of your property to turn around and say "You know what? Nevermind. We're doing our own thing". A good-standing partner also wouldn't let that fly. Considering WB and Universal still work together and continue to add new experiences (Death Eaters, Creepshow) and seeing how there's been nothing about any pushback, lawsuit, etc between the two, it stands to reason your thought process about the situation is not exactly sound.