Is it risky to book a cruise sailing right after COVID-19 ban is lifted?

We do not think it is "risky," because if the cruise is canceled, they're just going to refund your money again. The cruise lines are only going to reopen the cruise if they feel it is totally safe, so I wouldn't say there's a health risk. There's no risk on the cruise fare, because if they cancel it then they'll just refund you the money. The only risk would be hotel or flight reservations. So we recommend looking at their cancellation policies before you book, but if you're in a drive market, just booked the cruise because if it cancels, then you'll get your money back.