I think his point is that the option is "strengthening the flag", i.e. increasing (the already really high) German standing in the world through economy, diplomacy, alliances.
The odds of Russia attacking Germany, even indirectly, are absolutely minimal. Germany is one of their main export countries and is one of the leading countries in the EU (more big trading partners for Russia) plus a member of NATO.
On top of that, Russia is a shadow of the USSR. A bit more than half the population and an economy which in relative terms is a dwarf (i.e. the USSR had a much higher share of the world economy than Russia does now). Let's say they occupy Germany after a "clean" campaign. Their economy would be completely shot.
And let's not go into guerrilla warfare territory, they couldn't even control Chechnya, let alone 80 million educated people which would surely get foreign support in terms of arms and supplies.