It would be nice if this could make it for 2.81 but it might be too late considering we are in BCON3
Quadriflow remesh is an operation that you usually run once per object, so it does not make much sense to have it in the topbar. In 2.81 the Quadriflow operator is not completely finished to be used in a sculpting workflow. We should start thinking on how to make a clear distinction in the UI between Voxel and Quadriflow, as they are not different alternatives to do the same thing.
On the other hand, we have a shortcut for running Quadriflow in sculpt mode. We should probably remove that instead of adding Quadriflow to the topbar.
We may reconsider this once the final Quadriflow remesh/convert to multires operator is finished.