Considering that the authors used to be a politician with personal experience in this particular field I wouldn't discount his opinion. Especially not based on where he published it. Based on facts or not, who'd publish something that takes the side of the 'evils right wing populists'? Not the MSM.
I also have personal experience in this particular field and can think of any number of reasons the debate took that long: They knew the decision would be controversial and wanted to make really sure they got unassailable arguments. They were actually looking for a way to not cut the list for fear of the controversy, and were searching for arguments against it. The AfD member on the board was extensively arguing against cutting the list (highly likely, actually), etc. If the debate had really taken just ten minutes, this guy would also have claimed that it showed the result was already set by sinister forces in advance.
Divorced from personal political opinions - I saw "Sympathizers" this week (currently available in the arte mediathek in German and French), a film about (mostly) artists and intellectuals who were accused of being same for the Red Army Faction in the heyday of the latter's terrorism in the 70s. Made by the son of actress-director Margarethe von Trotta, who was counted among them along with her partner Volker Schlöndorff and others like writer Heinrich Böll, which gave him easy access.
Despite his personal involvement - seems he was present as a ten-year-old kid when Italian police raided Schlöndorff's holiday retreat in search for some terrorists of the Red Brigades - he suceeds in developing a multi-faceted image; some of his interlocutors are rather defensive about their views back then, some rather candid that they were wrong; the son of Heinrich Böll is still bitter about the political attacks by government and media figures on his father, which he blames for his somewhat early death. The interviews are juxtaposed with period statements and critical movies.
Whatever you make of it - what I find striking and ironic are the parallels in attitude and language from both sides back then to the current discourse with the changed background of right- instead of left-wing extremism and terrorism, like the murder series of the National Socialist Underground and the recent assassination of Walter Lübcke. The accusations against sympathizers that they're enabling the violence of anti-constitutional actors from politics and media, and of the state acting quasi-fascist by those so labeled, the debates of what is a "sympathizer" in the first place and who gets instrumentalized by whom, are basically identical.
Meanwhile, though the Greens have slipped a couple points behind CDU/CSU again in national polls as the bandwagoning effect after the European elections wears off, they are still comfortably above 20 percent and are currently projected to win up to 51 districts directly if elections should be held this week.