It's just the theme of the day, unfortunately. Games Workshop has cancelled Warhammer Fest 2020 and other events all over the world. It's just not a good time to be getting together in big numbers.
From the announcement:
We value the health and safety of each of you, our wonderful community and the wellbeing of our staff above all else. It is with that in mind, and with a heavy heart, we announce today that Warhammer Fest 2020 and all scheduled events at Warhammer World and the Warhammer Citadel Cafe are cancelled until further notice. The Warhammer New Hobbyist Expo will also be postponed.
If you’ve already booked your ticket for any of these events, you’ll get a full refund very soon.