That divisions will be composed by men that once the war end will want to go back home and stop fighting, even doing simply garrison duty will be not accepted and there will be revolts as happened in RL with the entente
France occupied the Rhineland from the very end of the war to 1920 in exactly the same circumstances and Ober Ost stayed in Russia until 1919 despite losing the war. Saying a victorious Germany couldn't do what it did do and what France did isn't much of an argument.
France can 'simply' go to a hyperinflationary phase making reparation moot, the Roubles become worthless due to the civil war and same for France.
The gold is still good, and if France starting deliberately trying to shaft German reparations then Germany will increase their occupation; the French occupation was extended 3 times, they occupied Frankfurt in 1920 and reoccupied the Rhineland in 1923, so Germany can do all that.
And what the Kaiser say and what will really happen are entirely two different things; it will not the first, second or 100th times that promise will be broken during that war and after. In poor words, no Germany is not that magic semiomnipotent entity that by some divine right will skip all the social, economic and political troubles that afflicted Europe in OTL in the immediate postwar, expecially due to her being overextended and with her two biggest allies on the verge of implosion plus much of her new subjects not really happy of the new management
The Kaiser and co weren't happy with what he had to promise in the Easter Message, but by 1917 they knew they couldn't deny 10 million ex soldiers their political rights without a revolution which was why it was publicly announced to the nation.