“Exactly. It would guarantee the U.S. wouldn’t blow it up again.”
Stupidly bald assertion, but let’s examine the rest of your argument without getting into who did blow up Russia’s imperialist bridge to a peninsula to which they have no contiguous land access. The only way that Ukraine can get grain out is by Putin’s leave? Ever hear of Odessa? Or the Baltic sea? Or railroads through Poland, Moldova, Serbia, Slovakia and Romania? All the grain deal was meant to guarantee was that Russia would stop messing with Ukraine shipping on the Black Sea, so Africa and the Middle East would catch a break. So now they won’t stop messing with the shipping? They will risk a confrontation with Turkey, a NATO member, should they happen to attack one of their ports? Oh, well. There are all those other aforementioned routs. Look on a map.
Not my assertion - Russia's.
If the West wants to play the grain card again, Russia would be wise to force that grain across the replacement bridge that the West pays to rebuild.
That's not a stupidly bald assertion. It's the same one used for any chokepoint such as the Panama Canal, the Suez Canal, and fuel pipelines. You want to ship your merchandise; you're going to use our rail, trucks, pipeline, canal, or bridge.
John Kerry and his cronies have been cashing in on millions decades by forcing natural gas shipments by tanker to Massachusetts instead of by pipeline. They stop any push to have a pipeline built. They get all the usual Leftists out front: https://ma.mothersoutfront.org/what_we_need_to_know_about_the_pipeline_fight