It's hard to compare a fusion plant and a geothermal plant if we don't know how much energy a single fusion plant could produce. Are there any estimates on that?
After 2014 they expanded the volume of that putative reactor by a factor of 100. Also, fitting on a truck was always assuming no neutron absorbing blankets (which have to be ~1 meter thick.)
"A reactor small enough to fit on a truck could provide enough power for a small city of up to 100,000 people."