That’s a pretty small farm, like less than half an acre of tomato plants, perfectly plausible that a vindictive neighbor carried out an attack normal people would only fantasize about. Doesn’t look like 2-4-D exposure at all to me...not roundup. Looks like a water issue, like the cucurbits got watered with salt. I am curious what his irrigation supply is or if is a private well.
Small farm pr not, that’s pretty outrageous. And depending on what was used is the soil even still viable?