Vance, it seems to me that what you say makes the technique I proposed quite possible, and safe, (assuming Vic might WANT a different angle, which she doesn't). The technique of using a die grinder through a small hole to hollow out the heart wood leaves only the sap wood and the everything external to it. The heartwood is hard and inflexible, the sap wood, is not, and if done properly the tree is left with only a very small scar and an area of markedly increased flexibility. The heart wood is also entirely dead and serves no function except structurally: it is entirely expendable. The sap wood must remain, as, of course, must the cambium, and the technique leaves them largely uninjured except for the small hole or groove through which you go in with the die grinder. Even somewhat extensive damage to the sap wood is well tolerated in most trees, as long as a thin rim is left intact below the cambium - it really doesn't seem to require all that much finesse, just understanding.
In the case of this tree of Vic's, there would not even need to be any damage from an entry wound at all - there is already extensive deadwood exposed at the crotch where one would go in. It's also clear that there is some flexibility to this wood as it is - several branches have been bent fairly extensively, it appears, using standard techniques. While they are much thinner than the area I propose bending, they are either thick enough to contain at least some heartwood, or point to fairly thick and flexible sap wood, and I assume, a cambium that survives bends well.
If Vic WAS interested, the technique would be easy and very safe IMO. I've learned and practiced this on a number of my own trees of various species since Dan Robinson introduced it to me several years ago. It has made otherwise impossible trunk and branch manipulations quick and easy, and there is no unsightliness to the result, AND I have yet to lose any distal portions. I've also watched Dan do this on several of his own marvelous trees, with easy and healthy results, and seen a number of other trees of his where such work done previously has turned out admirable transformations. It's a very powerful technique to have in our bonsai armamentarium.