Not sure that tendency is at all strong; how many rams horn failures have you seen over the years?
The trouble with this 'defect' is that we all have Shigo's words and images burned into our brains, creating an impression that may be way out of scale with the reality. In Shigo's words, this...
2.5 seasons was plenty to occlude--nice! Good vigor!!
Brittle cinder is not nice though...Time for soil replacement imo.
Maybe install mesh across the inside to speed closure? Might make a difference, might not...
O, and--contractor experience can also bias judgment; not sure what difference that makes. It's cloudy either way!
I'd like to see the questions more straightforward but that's just me.
1.5% 2,4D? Do not over apply, especially under the drip zone of desirable shrubs and trees as some of the control ingredients are root absorbed. "
Maybe expand your rock circle to or beyond the branch tips.
How is the desire to remove all limbs over the property understandable?
Why is the root loss more than likely to kill the tree?
Details needed to understand the situation.
Macrodrilling in dissection is fine but it's also a really good way to spread decay.
My thought on the site is to mulch 4" all over and prune back any bad leaners.
Is the tree a named cultivar? Looks like a graft union at grade. Roots are too deep regardless.
Good advice re finding the roots and posting the label.
" Obviously removal was high on the list." NO way to say this without a competent inspection. Hustling removal work on uninspected trees is sketchy to start with. It all goes downhill from there.
Arborists care for trees.
I saw these guys demo this in 2011; great stuff! https://treenet.org/wp-content/uploads/2017/07/Habitat-Paper-Final-Pat1.pdf
I do some habitat enhancement in living trees--bore cuts in the ends of branches for birds, trunk slits for bats...a little common sense goes a long way.
I hate to see...
I can't juggle or ride a unicycle. But I can google and see no reason why info cannot be shared, with disclaimers. IANAL, but...
But anyone who asks for legal research is going to be charged at an attorney's rate. ;)