He is correct: not all fungal activity is detrimental to trees. The relationship between trees and fungii is complex. Before insulting the integrity of someone, perhaps you should enhance your own study, then you would be in a position to argue the point with more grace and lucidity. My practical experience (in south east of England) with Cherry trees is they are poor compartmentalisers, and are notorious for rot when wounded. Cannot say anything about ants really, as I know little. Can say though, I live in a house built in 1867, which was left unattended for years ( became quite decrepit), was revamped, then not looked after much, recently two different types of ants became visible, red and black (with wings) both left small mounds of the substance in which they were staying (brick, plaster etc.). It is entirely possible, and probable that there is rotten wood in the house.