While no medication is 100% safe taking Hep C treatment is much safer than leaving the disease to run its course.
Diabetes and blood pressure treatment is not a contraindication to using Maviret although it is possible that the diabetes or blood pressure tablets he is currently on could interact with the Mavyret.
Drug interactions can be checked here:
The surgeries don't impact on the treatment.
The best way to ensure your husband continues to have a normal active life through his 60s and 70s is to treat the Hep C. There was a big study looking at 33808 patients in 3 US Health Systems treated with these medications published in the Journal of the American Medical Association just a week or two ago:
Are patients with hepatitis C who receive direct-acting antivirals at increased risk for adverse events compared with those who do not receive these agents?
In this cohort study of 33 808 patients in 3 health systems, direct-acting antiviral exposure was associated with lower odds of experiencing the following adverse events: death, multiple organ failure, hepatic decompensation, acute-on-chronic liver event, and arrhythmia.
Concerns about safety risks based on analyses of the US Food and Drug Administration’s Adverse Events Reporting System did not appear to be confirmed, suggesting that dispensed direct-acting antivirals may be safe for patients with hepatitis C