Nothing in this epidemic has been guaranteed. People made assumptions based on incomplete or simply bad data. However, had Disney's gamble paid off, Universal people would have been... upset... that Disney offered an incentive and Universal didn't.
I actually think Disney did make a misstep, but that misstep is not letting people who rebooked on
free dining continue that rebooking in a similar window (Spring through late Summer) 2021. I do believe that has been Disney's biggest misstep.
Universal's big misstep was putting 6/1 as an opening and then having to go back on it. Disney has never said when they will reopen. Regardless of what people want to believe to justify their decisions. Universal literally told people when they would open, and it's very unlikely they will make that happen.