I think the fact of using the excuse that “The reader draws his own conclusions” is really an act of laziness as you yourself say, it's as if the author has no idea what he is doing and doesn't know how to finish the book. So it happens in some movies, the endings are just bad.
I think this virus theme can be exploited in incredible ways and they just didn't know how to do it in this book.
Oh yes, SO many movies that I really enjoyed, up until the ending! Everything feels so rushed and crammed together, we need originality and creativity again 😔
Thank you for your comment and enjoy the weekend! 🙏
The conclusion and denouement are the hardest things to do and require considerable writing skill. I believe you should have the conclusion mapped out at the outline stage or you can get caught out.