What hes saying is if Judgment Day was really stopped, the audience would leave with no recollection of what had happened because we would be in an alternate universe where there was no Judgment Day meaning no terminators, no Skynet, and therefore no show. Its actually a pretty legitimate plot hole and will probably ruin my enjoyment of the attraction forever now
Also, the filmmakers never truly envisioned 2015 as what they depicted on screen...they always knew they were being crazy in their portrayal because they were smart enough to realize if they actualy tried being accurate they would fail. 2015 in the movies is supposed to be wonky and overstated. The main factor in BttF's demise was low ridership, with the old ride systems providing nausea and headaches and the IP falling out of public favor. It operated at less than half capacity in the days leading up to its closure. The way Universal sees it, there isnt enough interest in Back to the Future to warrant any kind of special ceremony. Although I guess with Kong on the way you never know for sure...but Id still be surprised to see them bother doing something for one day based on a ride that closed due to unpopularity.