What else were they supposed to do in the circumstances??? I think you're being really naive here if you think they are doing something wrong. Why wouldn’t they delay the opening for the “visitor wave”, they need visitors to make profit, they want to maximise the effect, they’re not running a theme park for funsies!
They would have wanted to open in 2020, believe me they don't want that capital outlay sitting there and not bringing in visitors. They would have then been told to hold off until 2021 (eventually), unfortunately communication doesn’t always travel correctly, especially in big organisations. I work in marketing and we’re often the last to hear about changes in plans even if we’ve designed a campaign for the last 6 months. Plans change, things have to be done on the fly especially in unprecedented times like we’ve had the last 18 months!
Ultimately what you or I think doesn’t matter to them, we’ll still visit anyway, what matters is getting the GP into their park and the best way to do that is to have a brand new attraction for a new season.