Alas hurling abuse does not change the facts. There is no pseudo science or any science at all nor do the authors claim there is. Nor have the authors invented any scientific or any other 'method' They have applied a recognised and valid statistical analysis to data which has shown what it has shown. They also offer some hypotheses as to the mechanisms. You may disagree with those hypotheses but have so far failed to provide an alternative one.
So effect of the Holocaust in Russia initially negative now in fact vanished (in politics and economy).
And yet clearly it has not. Indeed not only has its not vanished but has, in fact, grown over time. Just because you don't want to believe it doesn't make it not so. Fervent belief, alas, does not make the facts go away.
Let's look at Ukraine. There were much more victims of the Holocaust (I mean percentage and absolute numbers) than in Russian Federation. But electoral support of the Communists in Ukraine was low after collapse of the Soviet union and now the Communist party is forbidden. At the same time GDP per capita in Ukraine 3 times lower than in Russia.
But pseudo-scientific 'method' invented by the author predicts massive support of the Communist party in Ukraine.
In fact, in the main, the hypothesis (not the 'method') is substantially supported by this example - the GDP is lower. That it has not translated into votes for the communists is - to hypothesize - because Ukraina is a seperate country where firstly communism is equated in many minds - as it is in Poland for example - with foreign Russian domination and oppression and, secondly, is in any event not an electoral option now for Ukrainians, as you yourself point out. A good reason why analysis should be limited, as far as possible, to comparable entities.
It is so insignificant number that if even Hitler managed to murder all Russian Jews then the middle class would not be affected in any substantial way.
And that would be a reasonable argument if the Jews were evenly distributed but they were not - a point you not so long ago stressed yourself. Therefore the loss of Jews had an uneven impact on the middle classes of different regions and the authors have found a clear independent relationship between those losses and subsequent evolution.
The middle class in modern Russia is big enough and ethnically is mostly Russian.
Yes, but that is not really relevant - it cannot change what happened in 1941-45. Since the evidence is that the effect has grown not diminished, it is likely that it is the impact at that time that was crucial.
Life goes on.
Indeed it does. But it has clearly gone on differently in the cities occupied by the Germans that had high Jewish middle class presence prior to 1941 when compared with cities that did not. If you can offer a more convincing hypothesis why this is so than that offered by Acemoglu ey al, I am keen to hear it.