They do have the tech for terminator genes, and I think for corn too. Basically, the corn seed is edible but it can't grow. Despite people freaking out about them, none have been marketed and companies have pledged not to sell them. Though feel free to speculate if that's because of public pressure or not.
That would be a terrible thing to sell. A farmer plants the seed, the plants grow, the pollen drifts far and wide, and the farmer next door winds up with his crop not sprouting next year. And then come the lawsuits...
That's not how terminator works, nor is that how modern agriculture works.
Fields for seed are far removed from productive fields. It's trivial to keep them separate from contamination; in fact, it's essential that this is done to make selfs or directed crosses.
Terminator was made to address concerns about transgenes entering the wild. Think of it like a mule; you still have offspring, but they're infertile. That's what terminator does. It cannot ruin a crop. Seed is still made and can be sold and eaten. It simply is infertile.
A construct was first developed by the ARS and USDA, and they were quite right to pursue this. It's a useful technology.
