Yes, you are right, there are better alternatives but the customer is not interested in them, and you have wasted your time, effort and breath on this one who just gets somebody else to do it.
In other trades there are regulations and enforcement ... we have none. So, IMO we wouldn't be doing anything illegal, and perhaps it will take a few more failures (man induced) to wake up these politicians and regulators to do something about it.
In a years time if she moves out and the new owner doesn't know what has been done and the tree fails ... insurance will cover it, if somebody is injured and an inquiry proceeds the original owner will be the culprit, and if she's no longer around (deceased) then what?
Wont win against the tree company because they have their disclaimer.
Might as well sue the govt for not prohibiting the exercise, they are the negligent party, the contractor has gone the extra lengths out of his goodwill and knowledge to inform the customer of their ignorance ... something most other contractors wouldn't even know about let alone do.
It's a huge kettle of fish, but being a good guy with high morals and ethics is costing you and not your ignorant competitors. I'm in the same boat, sometimes I walk away, sometimes I don't ... but as time passes the more I wonder why rules don't change and the more I realize there are no rules.