But you can still use the app you paid for during the rest of your life. Nobody is forcing you to do updates to your phone, certainly Pocket Cast aren't forcing you to update your phone.
But yes I don't think you can disable updates only for particular apps.
If we're doing "but"s...
But the original agreement was for updates for a lifetime. Of course people are going to be upset if they were promised one thing and ended up getting something else.