Not a theory, actually. I was a mod for a Facebook brug group for a while.
So while I'm not a hybridizer, I do have some knowledge and I still have brugs, tho not as many as when we lived in the PNW.
Absolutely, one may preserve the Y, if it's cut off the main plant when pruning, and keep that one for oneself unless there are multiple Ys - yes this does happen.
Loss of the leader served to make the plant less of a standard, more of a bush. Since the Y typically happens at the point of growth, I then had to wait until side branches were well enough grown to form Ys.
The picture in your post above is of a Y with blooms. The first bloom will typically form in the bottom of the V part of the Y, where the two side branches form. Mine that formed there always dropped, but it looks like yours held. Congratulations!
