I would have to disagree. In hardwoods the top part of the branch pulls the branch upwards by forming denser wood but in conifers the bottom of the branch produces wood with more lignin which supports from the bottom.
You can check out "reaction" wood and read about the differences in various trees.
In practice there is probably some variability depending on actual branch position.
The top is still the tension side of the bending force a branch will be subjected to but I think this is mainly about which side of the branch is comprised of the most desirable wood, growth ring size notwithstanding.