So if the red states votes actually counted more then it would be an advantage? So there votes already don't count enough?
It's all basically conjecture if you want to start using that as a response, but it still doesn't change the central portion being mostly red.
You said "the US has a lot of guns, but most of them are owned by a small percentage of the population." So who owns them, other than the military?
So guns would only useful for offensive purposes in this case? Why?
Well I didn't think I would have to list every single thing the central portion could do. I guess I'll name a few more things they would use to persuade, like oil, coal, waterways, air travel.
Imagine not being able to fly straight across the country and having to go around the central portion every single time, where as the central portion would mostly only need to fly straight up and down. In terms of everything they can use to their advantage, this also wouldn't happen slowly over time, it would be put in place very quickly so the coasts couldn't simply plan ahead and import more overnight. You also failed to address the raised prices of everything and how that's going to impact the 'wealthier' coastal area's. You also haven't taken into account the water needed to grow that food and who's growing the food. How do you easily and cheaply grow your food if the central portion controls most of the waterways? You think because a Conservative farmer is in California, that they will side with their state or the coastal area's together? They are likely to sell to the central portion who is paying more on purpose to make sure the coastal area's have shortages. With the prices being so high, and having no other choice because it happens so quickly out of the blue, the central area will be able to afford it as well. Will the central portion also just let the coastal area's import as much as they can without hassle? What if those shipments are turned around or just delayed? What if the central portion purposely uses it's excess funds to gobble up as much imported food as possible so they have a monopoly on it, so the coasts are basically forced to purchase from them one way or another. The red states would also instate conservative policies and will get rid of illegal immigrants, reverse abortion, cut back on welfare, etc, which will change any purple states to solid red again. The border states could even 'open the border' and allow the immigrants to easily cross into the coastal regions while keeping them out of the central portion for the most part, forcing the coastal regions for focus more heavily on border security. The possibilities are endless.
The point is the central portion could easily outlast the coastal area's and it wouldn't take long for the coastal people to push their Gov to make a deal and get things back to the way they used to be.
I want you to know your scenarios read like a Ben Shapiro novella or fan fiction on r/trump.
edit: or the political version of "my dad could totally beat up your dad".