True, but I've always made the assumption that anyone attempting terraforming of Venus in the distant future would also like to grow crops and plant shade trees. Larger plants like these require a higher atmospheric CO2 level. It's an interesting point though...I wonder where the "balance" would be, and how low we could actually drop the CO2 levels before agriculture lost its viability.
that will only work if they get the relevant construction permits from the venusians...