Selling a business usually entails a lot of energy and time. Selling at arm’s length always involves a lot of uncertainty.
And with a successful product the owner has certainly received offers and will have an informed opinion about the type of people likely to buy and the offers that would kick off negotiations…there is a reasonable chance the owner has explored selling already.
So my guess is that shutting down and treating existing customers very well using a download is the best thing for actual customers (unconverted users are not customers).
Or to put it simply, doing right by customers might not be practical in any probable sale.