Fair enough. I get that the average punter might not know exactly where the boundaries of their property are. I'd expect that it should be fairly standard that it would at very least ring a bell with a councillor that a project bordering their property may involve a conflict of interest, and it should be checked out before any approvals go ahead.
As for him having no part in the decision, the P&J version of the story seems to suggest something quite different.
https://www.pressandjournal.co.uk/fp/news/aberdeen/1229641/pay-200000-fix-council-bosss-boundary-wall/