Well the whole 'nudge' (I'm never sure if that's a better or worse term than libertarian paternalism) concept is about the government making a determination of the best choice to make then non-coercively influencing people into taking it. The problem is when it stops being non-coercive, or when it is used in the place of open persuasion and debate.
For example, when it comes to advocating healthy eating you put in place gentle policies that make healthier lifestyle choices easier. Simple things like rearranging the layout of supermarkets and cafeteria can adjust eating habits and encourage the 'right' choices. Adding clear and obvious nutritional labelling to food makes people more aware of their diet and makes it easier for them to keep track. But these things need to be discussed and understood, alongside public education and debate over their value and intent.
Once you start losing those factors and are used to the government determining and unilaterally implementing programs to modify peoples behaviour for their own good, nudges probably won't stay nudges for long.
It's always best to think about these things in areas you don't want to be restricted in yourself, or where you disagree with majority (or at least strongly influential and likely to be shared by future leaders) views. A nudge towards healthy eating we can all agree with; we can probably justify a shove in that area from time to time. But when it's something more marginal I think we need to be extremely careful. It's easy to justify government action when you start off non-coercive and gentle, but once you have made that first determination that action is justified it's all the easier to keep pushing till you start seeing results.
The stretch to Stalinism is somewhat misplaced I think, and it's not really a valid comparison between the two. But knowing the authors I'd say this is more lazy shorthand than a genuine political comparison. Knowing their views I can put money on both supporting Obama over whoever in the next election. At least so long as the American Communist Party or Pirate Party don't have valid candidates.