A. Most of what you hear is not to use pruning paints anymore to cover wounds on trees. They are considered primarily cosmetic and do not assist the tree in healing. That is true.
There are claims and some research to support the idea that pruning paints may actually cause some harm to a tree. But even so, they will not kill a tree or severely weaken it.
Pruning paints or similar compounds are still used in the propagation of trees such as grafting and topworking. The primary objection to using pruning paints is similar to why we no longer recommend using Band-Aids to cover a healing flesh wound.
In this particular case I would go ahead and try it since the benefit to you may get from using it may outweigh any negatives to the tree.