Boy o boy
That's a shocker and close to the house. Looks like a nice house. Maybe drop in and have a chat, find out if they knew the consequences.
I find most people have no idea but dig in and defend the practice so they don't look dumb. But I bet when you walk away they feel like a real goose.
But here's a motivational angle, once the client is informed then insurance has a right to deny a claim on the negligence factor for not taking action to remedy the fault. Problem is you don't know who their insurance company is however you can let them know it's on public record and give them the link to this thread.

Then invite the dominant insurance companies to the forum with a link to the thread ... I have done this already many times.
An insurance guy told me there has to be evidence of notification for them to deny a claim ... well, here's a pretty good place to do that ... you could even enter the address just not names ... nothing illegal in that. So if some-one was to search the address they'd get the history.
It's time to get the insurance companies to realise many of the claims pertaining to trees could have been avoided. Did you see the thread I started called "
Ignore it then claim insurance"?