first thanks for your quick reply!
If I would apply this filter as you wrote, wouldn't this affect all WordPress plug-ins?
If that's the case, this obviously would not be a very good idea, because maybe some plug-ins really need this for security reasons.
But I absolutely don't see why this public preview link needs to expire as I
1. explicitly enable the link (and I can disable it again at any time) and
2. this is not a public link, but I only send it to few people directly (that should review my post) and I want it to be active till I disable it again or I just publish my post.
Therefore there is no need for automatic expiration - at least there should be an option to disable it.
Best regards and thanks again