That would be weird. After all, Stein and Hardenberg in Prussia are no exceptions. You have Montgelas in Bavaria, Reitzenstein in Baden, Normann-Ehrenfels in Württembergh, or the mostly French reformesrs in the Kdm of Westphalia and the GD of Berg. Rationalization of the administration and removement or reduction of traditional privileges stunting ecomoic development were so very much a Thing that it is difficult to see one state stasnd completely aside.
But then, Mecklenburg managed it almost, so if you get a Junker-dominated government and a king completely disinterested in reforms, it might happen. Unlikely but not impossible.
Hm. If Friedrich Wilhelm III. gets himself killed by accident when fleeing from Berlin to east Prussia, the new king, FW IV, is only eleven years old. Regent would be his father eldest surviving brother, Heinrich. Who suffered from permanent poor health. So there might be no central push for reforms.
But still, most you can probably do is delaying the reforms for a few yearws. Whicdh might still have big consequences wrt a reduced role for Prussia in the defeat of Napoleon, with Prussia becoming an informal or even formal client of Russia and getting far less territory back when Germany is carved up by the victorious alliance.