What? You could repair the damage to the pipeline. If someone could replace Putin by promising to sell gas to the Germans, the fact that the pipeline is currently damaged would not be an obstacle.
It's also not the case that Putin needs false flag terrorism. For one, he is already in power and has already started the war. Two, if he needed an example of US or Ukrainian forces blowing something up to galvanize his position - he has plenty of real world examples of Russian things getting destroyed - he doesn't need to manufacture a new one.
It was damaged beyond repair, certainly beyond a quick repair. If the plan with gas extortion was to break the will of Europe over this winter, then no alternative to Putin could offer any relief after it was blown up, decreasing the value of backchannel negotiations.
It's also not the case that Putin needs false flag terrorism. For one, he is already in power and has already started the war. Two, if he needed an example of US or Ukrainian forces blowing something up to galvanize his position - he has plenty of real world examples of Russian things getting destroyed - he doesn't need to manufacture a new one.