In the first place, what was in it for Germany? They were still up against the Western Allies, whom they considered more dangerous, and who were doing the really effective stuff that would bring down Germany, namely the British blockade. Without the eastern territory Germany hoped to annex to feed itself, they were in danger of being starved out by the blockade and the US was leaning into the fight in spite of Wilson running for reelection on a peace platform. And even if it was a good deal, if the departure of Russia could have swayed the Western Allies to give up, there is no evidence that Germany had the sense to take it. They effectively finished off Russia well ahead of time as a fighting force, but kept grinding ahead on the Eastern Front until they got the Treaty of Brest-Litovsk, which some historians consider a critical delay that gave US forces time to get into the fight.

Back to the issue of Germany accepting Kerensky's overture, as noted by the author, "Germany" has little to do with the decisions being made, they were effectively being made by Ludendorf & Hindenburg, both of whom were, in the factional contentions over national strategy in the Germany armed forces, easterners. The German officers were sharply divided on the question of which direction Germany should concentrate her military efforts. The "eastern" clique pushed for the old Drang nach Osten, to acquire Lebensraum and especially, agricultural resources, with the goal of making Germany self-sufficient. IIRC, the westerners sought to impose their will on the Western powers to achieve political & diplomatic advantages. Ludendorf, Hidenburg & the other men of the eastern chapel had defeating Russia and expanding across Eastern Europe as the principal war aims. Accepting peace with that goal in sight would have been out of the question for them, absent Anglo-Franco armies swarming across the Rhine, which was never going to happen. Hindenburg told an American reporter after the war that what made them give up was the persistence of the American attack in the Argonne. Without that show of determination and commitment, the Germans had been confident that they could stave off any attacks by the British & French indefinitely. America's entry with the vast material wealth, industrial capacity and a much bigger, and heretofore untapped, manpower pool was the game-changer, and Argonne Wood proved they had the will to use it.

Essentially, the German leadership was far too confident in 1917 to accept a peace offer of status quo ante bellum. At that point any such offer would be seen by most powers as a sign of weakness, and they would not have accepted it. France, maybe, depending on who happened to be in charge at the moment, but the UK's military leadership grievously misled their civilian government as to the true state of their forces and situation AND were too incompetent to realize they were getting beaten like a drum. So England was not about to sue for peace or accept German offers of status quo ante, and without that, there was no reason for Germany to back down in the East. They had all but exhausted the capacities of the Russians, and had effectively knocked Serbia, Romania & Italy out of the war, while tying up substantial British forces in Turkey & Greece with minimal commitments of their own, and surprising performances by the Central Powers' second team. In the minds of the powers that be in Germany, there was no motivation to stop and doing so would have forfeited the raison d'etre of the whole war in the minds of the men in charge.