Stung by claims that their product could alter the Earth's atmosphere and be a disaster for humanity, the dominant company in the industry launched its own research project in the 1970s and 1980s, only to find out that the claims were correct.
If, when, tobacco-style litigation ensues against Exxon and possibly other fossil fuel companies, the strong contrast between what Exxon said and what DuPont said to their investors and the public could be a powerful legal argument.
Leaving the legal issues aside, there's also the contrast between not just the statements but also what actions the two companies took. I don't claim it would have been feasible for Exxon to plan to get out of the oil business by the year 2000 (for one thing, CFCs were only a minor part of DuPont's business). However, Exxon could have taken the lead on starting to plan alternatives, and that's another key difference between the two companies in the 1980s.
Several years prior to 1988 and the official change in tune, DuPont started developing CFC alternatives and subsequently made a good business out of the alternatives while winding down CFCs. By the early 1980s if not earlier, Exxon had a comparative advantage over other oil companies in directly understanding the climate challenge. The renewable energy business was non-existent at that time other than large hydro - Exxon could've been in at the beginning to become a major player or the major player in what today is a big business with huge growth potential.
Other oil companies like Chevron and BP have put a toe, or more than a toe, in the renewable business. Exxon could've followed the DuPont model and have been way ahead of those companies. Instead as far as I can tell Exxon does nothing.
Exxon blew the opportunity that DuPont seized, and it didn't say what DuPont said.