Whole30 doesn't bring about higher blood pressure, but for those of us with strong family histories, it also probably won't keep it entirely at bay forever. More's the pity. I speak from sad experience. My first Whole30s actually lowered my bp to where I could get off of medications for a while. But the bp came roaring back, and it absolutely does not matter what I do, I need two medications to keep it in a range that doesn't cause my doctor to have to do deep breathing exercises in order to calmly keep talking to me about my bp.
This is one of the things I do not like about being human. Urgh. Anyway, when it comes to the bp your husband is registering, medication is not generally the first course of action. Watching and waiting, taking bp fairly regularly for a while, and monitoring how it goes, while following some of the advice Chris Kresser and others like him give, is often very helpful.
At the end of the day, though, eating healthy whole foods is not the thing that causes us to have high blood pressure. Some day someone will research what actually causes it, and then we can figure it out. The hardest thing for me to accept on my journey to accepting my own high bp is that for 95% of us who have high bp, there is no known cause -so we are always and only treating the symptom. It's kind of freaky. I can't understand why researchers wouldn't be interested in the causes (and I'm talking here about those causes that get passed down in family history) but I've noticed that high bp tends to be treated, by the medical establishment, like a lifestyle choice rather than a condition. I'm tiny, eat healthy, and live as stress-free as possible (haha) and I don't fit any profile for high blood pressure, and still, here I am. It's not a lifestyle choice that brought me here, and I promise it's not for your husband either.
Here's hoping that when he gets his bp checked next time, it's back in the usual range. All good thoughts and happy Whole30ing to you both.