Kohn explicitly says that allowing negative natural consequences to happen when you can foresee them (even if your child does not appreciate or is stubbornly arguing with you they won't happen) : that that is a form of punishment. Tsk tsk. Whereas Natural consequences that you didn't foresee are just bad luck (i guess). And Natural consequences that your child likes are perfectly fine to endure (I guess).*
Actually he doesn't say you shouldn't allow the natural consequences to happen. He say that it's not because x (eg I am hungry because I haven't eaten my lunch) happens because your child hasn't listen to you that you shouldn't help him (eg give a bland snack to help him wait until snack time/the next meal).
* Showing your disapproval is another punishment.
Well actually AK gives a nice list of ways to show your disapproval to a child so I am not sure why you think UP is against any form of disapproval (Even though it is clear that some form of disapproval are less than helpful)
* Expressing praise is bad.
What AK says is catching children being good is like giving them a verbal doggie biscuit, this is a calculated attempt to manipulate them [...] Just paying attention to what the child is doing is a form of encouragement [...] There are times where it IS appropriate to say something ... this can be done by explaining the effect of the child's actions on other people (eg That makes things so much easier for me.), inviting reflection (eg How did you come up with that way of grabbing the reader's attention?) or asking rather than judging (eg what made you decide to give some of your brownie to Derrick?)
So it isn't about not expressing praise, it's about the intention behind the praise.
Tbh there is nothing new about that. Have any of you not be caught out saying 'oh this picture is beautiful' to your child who then looks at you and says 'no, it's awful'?
* Rewards or bribery are very very bad.
Yep completely true. Because rewards and bribery are about manipulating the child so he does what you want him to do and forgetting about RESPECT (In capital as this is one of the principles of UP. treat your child with the same respect you would with anyone else, that as you would with an adult)
* Saying "I like it!" is bad. Even if that's your honest opinion of something they've done. Too much like evil Praise. Much better to lie and refrain from saying your honest opinions.
See above about praise. AK has never said that you shouldn't express your opinion. Why on earth would you want to do that. He would probably argue that you should also try to explain why you like it/think it's great but really it's about being able to differentiate praise (which has an aim, to be make the child obedient) and liking something (which your own opinion about something). The issue of course is that both are sometimes entangled.
I am also quite sure that AK would be completely against lying to your child in these circumstances....
On the other side, a lot of parents (conventional parenting) will tell their child that 'their drawing is beautiful' when it's just a mess of lines everywhere so that they won't hurt their self esteem, they can see the child is looking for approval etc... Even though they don't think that the drawing IS actually beautiful. White lies seem to be Ok then....