Not all old trees have downward sloping branches. If you’re trying to emulate an alpine tree that has been subjected to heavy snow loads, that is a good way to go. But for trees in other environments, there are other ways to convey age even if the branches rise up, as they do here. You can remove branches lower on the trunk and create sparse foliage pads to make the tree look old. Sometimes you have to work with what the tree presents. In this case, I don’t know how easy it would be to move some of those heavier branches down. You might run into a situation where the branches leave the trunk at an upward angle and then bend down, which might look forced and unnatural.