It is common knowledge that you are inclined to advise extending a tree "BEYOND its useful life" on all 4 forums. I did not suggest removing this tree, but rather just let it run the course of its meager 25 year existence.
You answered your own question re "an engineered tree" (having no idea what I meant). This tree was cultivated to have a large shiny canopy with small fruit and in the process the final product was a tree too weak to support the load. Big disappointment to towns all over the country. My point re the engineered tree was not that other trees are engineered but rather that this engineering failed. Many towns ( and HO's) thought like you and after large sections tore off, the natural thing was to lighten the load (yeah I said it TOP the tree). This made for an extremely ugly tree in the dormant season.
This also pushed growth even faster than the already high growth rate and what did they have but a new huge canopy sitting on top of a compromised beam/stem. Bam, another and the final failure.
I stand by my quote on ants Guy, and could give quotes or multiples as I have all Shigo books and Sinclair as well, but that has never made a difference before. Ants are an indicator of decay, the primary problem when you see them or evidence of them. They may do some inconsequential damage beyond the mining of their homes I suppose.