This appears to be yet another demonstration that something the left wing are not actually saying is wrong, and that therefore the left wing is wrong.
The paper is attempting to rebut the claim that Scandinavian living standards are high
because they have a large welfare state. That is a distortion of the left wing position. The right wing position is that, although it is unarguable that individual benefit recipients are better off in the short term due to the state provision of generous tax-funded benefits, there is a long term harm to the economy as a whole which more than offsets this benefit. The left wing rebuttal of this position is that Scandinavian countries provide such benefits without suffering the predicted long term and/or systemic harm. To attempt to counter that rebuttal by saying 'But Scandinavians in the US are generally better off too' is to defeat a strawman.
Regardless of the levels of poverty in Scandinavians, whether in the USA or in Scandinavia, it is unarguably true that giving money to poor people will alleviate their poverty, at least in the immediate term. The welfare state has a clear benefit; to rationally oppose it, you need to show that it also causes harm, and that the harm caused outweighs the benefits. This paper does not even address that question. It presents a strong argument for adopting Scandinavian modes of thought and behaviour; it does not present any argument at all as to the overall net effect on
non-economic well being of all of the various benefits or harms that result from a welfare state.
Your headline should simply read "Scandinavian social norms help to reduce poverty". The article doesn't present a single shred of evidence for or against the overall value of a welfare state (despite the authors claims to the contrary); The author simply presents his belief that the 'economic rules' apply to Scandinavia, and that things would therefore be even better in that part of the world without the 'large government' policies that those nations have pursued. In doing so, he begs the question - his definition of 'even better' is based on economic measures, and not on the measures (such as the OECD 'Better Life index') that he uses to establish his position.
It is probably true that GDP per capita; unemployment rates; interest rates and other aggregated
economic indicators could be improved in Scandinavia by moving towards a 'small government' model; but this does not imply that such economic improvements would not lead to offsetting reductions in the non-economic components of what makes people happy.
Being rich is a good start on the road to happiness; but as the chart on page 3 of the paper shows, it's not everything - there are six countries that rank higher than the US on that table, and all of them are poorer than the US in purely economic terms.
Poverty vs wealth is not the only important issue; financial security is a vitally important element of happiness. Having a well paid job is great; but having a slightly smaller income is an acceptable price to pay for the certainty that, if your job disappears (or your ability to do it disappears, for example due to ill-health), your income will not fall so far as to completely destroy your life.
Welfare states are good for poor people; they are possibly bad for 'economies' (depending on how you define an 'economy'); they are undeniably bad for the (relatively) wealthy people who must fund them; and the overall result - whether they make people, in general, happier - is not directly addressed by the linked article. That at least six such states do better than the wealthiest nation on Earth even by the standards espoused in the article - which is clearly intended to give the opposite impression - strongly suggests that the overall result is better with a strong welfare safety net.
To anyone who has lived in fear of losing their job, (or indeed to anyone who understands the cliché that money isn't everything), that shouldn't come as a big surprise.