That's what happens when a man loses an election for you, but it seems that even Merkel's own party were wrong-footed by her swift revenge. At least, that's what CDU boffins like Karl-Josef Laumann, Norbert Lammert, and Wolfgang Bosbach blubbered, like so many admirals who aren't building the Death Star fast enough.
But it's a problem for Merkel. The thing about Norbert was that he was an ideal person to have as a CDU environment minister. He was mild-mannered, soft-faced, and – crucially – cared about the environment A LITTLE BIT. He was very good, for example, at making climate-friendly noises and generally suggesting we should pick up our litter. The last thing that a conservative government wants is an environment minister who cares about the environment A LOT, obviously, but they also don't want one who doesn't care about it AT ALL. That would be equally problematic. In Röttgen, Merkel had A) a good Green Party deflector and B) an easily overrule-able minister.
When he was in office, and something about all that nuclear sludge being dumped down a mine in Gorleben came up, the Green Party would often scoff at the way his Penfold-face crumpled as Merkel made him do the opposite of what he just said. The chancellor did this quite often, while occasionally praising him for his clerical skills.
But now he's gone, the Greens have been deprived of their lame duck. That's the problem with lame ducks – if you make their lame-duckness too obvious they get made into soup.