Merkel might have followed his idea but she made the final decision. It was Merkel (after Fukushima) who declared an end to nuclear power in Germany - pandering to Green voters.
The idea might well have come from the Schroeder Government but he did not make the final decision. In fact, the idea of nuclear exit is an idea of the Greens, Schroeder was pandering to the Greens in his coalition government back in the day. (Schroeder being SPD ("socialist"), Merkel being CDU ("conservative") and the Greens being the king makers back in the day - 2002 elections).
One has to remember that it was different times: the Greens were a serious alternative to SPD and CDU, one of their main ideals (since their foundation) has been an exit from nuclear (generally). So once they came into power with the SPD and Schroeder, they were naturally keen on asserting their influence.
Schroeder needed an alternative power source so he started looking to Russia. Russia was a serious partner in Europe, not only for Germany but all of Europe. After the fall of the wall, the policy of Europe was Russian integration into Europe. Why? Because this policy of interdependence of nations within Europe brought peace to Europe. Interdependence is - within capitalism - best achieved via trade amongst nations. Hence Germanys (not only Schroeder but german industry too) decision to accept (more) cheap gas and oil from Russia. The Russians were keen to bypass Ukraine and deliver gas directly to Germany, hence the idea of building the Nordstream 2 pipeline - an idea supported by the Schroeder Government and most probably german industry.
The Nordstream 2 pipeline was completed in Merkels times but it was never brought online. Olaf Scholz (SPD) made the final decision not to take the pipeline online because of Russias official recognition of the Donetsk and Luhansk regions as Russian. It was bombed - destroyed? - by unknown persons during the current war in 2022.
The result of these events has been raising energy costs in Germany. Which has lead to disenchantment in the political system, which in turn has lead to a shift to the right in Germany and a raise in the AFD. Ironically, it has now come full circle with a CDU suggesting an easing (if not removal) of the "Schuldenbremse"[1] ("brake on debt") - meaning that Germany is not allowed to borrow money above a certain limit. A policy that has destroyed investment in the country and lead to an evasion to risk-taking. A policy introduced by the CDU back in 2009.
In the end, it is all rather academic since we're now here and pointing fingers at the past is pointless. We're now facing a populist president in the USA, a populist Kanzler (prime minister) in German and chaos in Europe and the World.
For me, it seems that good ideas are always the success of those that commit to those ideas, never those that actually had the ideas. Bad ideas, on the other hand, are always the fault of those that had the ideas, never those that committed to those ideas. Unfortunately hindsight decides between good and bad ideas.
