If, in contrast, you let those farms and skill dry up it would be difficult to rebuild quickly.
I don't see why it's strategically important to the US taxpayer that one millionaire own it vs a different millionaire (or corporation).
Getting a domestic replacement in 12 months of belt tightening would still be a lot better than having to deal with several more years of that.
Also I'd expect that there are cases were we export X and import Y, and if Y was cut off we could switch to using X somewhat as a substitute. I don't know offhand of any specific plant foods where this is the case, but pork and beef illustrate the idea. We import about 15% of our beef. If that got cut off we could cut some pork exports and use that as a substitute. It's not a great substitute but it is calories that can get you through a crisis.