"He stressed that, if the worst came to the worst and one of the veg box clients contracted the disease, he wanted to be able to show any investigator that everything possible had been done to limit risk."
WTF?! When did we ever do everything possible to mitigate risk?
Then there some obvious points:
1. Clients can get it from others too, so how would he know it comes from you?
2. Clients can get vaccinated if they're so scared.
3. The vaccinated can still transmit this disease.
But maybe he thinks the vaccine isn't guaranteed to work for his clients .. so you better have it...
What a complete load of tosh.
If he wants to do everything possible, he'd have to stop his business. In fact, it's still not enough. Better still, top himself, before he might infect someone