Re: Far fewer . . .
Far fewer when you factor in the need for a functioning magnetosphere, possibly even the requirement of a large moon. You mentioned that, but I couldn’t even find the word “moon” anywhere in the pdf report.
Far more when you factor in that the study does not include Earth-sized moons around some of those Jupiter-sized habitable-zone planets -- and the giant might even be able to handle the magnetosphere need.
Dan