Your husband is in a very serious position. It's not simply a "lifting too heavy a weight" issue. The primary problem is large spikes in blood pressure, no matter what the cause! If he is doing something with the horses (very unpredictable animals), that causes an abrupt pressure elevations, in particular something that he cannot control - as often happens in dealing with these animals (as the physicians assistant tried to point out) - then he risks an uncontrolled bleed, which can be life ending.
In addition, I'm guessing that weight management part of the program, that IS under his control and a requirement, can force him to modify his diet in ways that are not good, from a liver disease standpoint (guessing he need to be lightweight). Our livers produce a number of very critical proteins that make us healthy. Any diet that is "starvation" oriented can be dangerous, especially when dealing with severe liver diseases. We need a minimum amount of protein, just to survive.
I was a very active athlete and competitive person. And I realize the realities that are a requirement in activities that your husband engages. But changes need to be made.
We're here to help out in anyway we can. Take care.
Your husband might want to get a second opinion from a doctor who specializes in hepatitis C. Varices are nothing to fool around with. A bleed can quickly become life threatening. There will likely always be restrictions.