the homeowner is responsible for taking prudent responsible action, whatever reasonable action they can.
if they denied your claim, you did exactly the right thing to contact the insurance commissioner's office.

you might be able to do some temporary shoring up? according to my insurance adjuster husband you have done everything right.

your policy is most likely only covering the cost of removing the tree from the building and damage to the house. they won't pay to haul the tree away even. and only if it hits the house

for them to imply that you are negligent is disingenuous on the part of your insurance company but since there is no damaged covered property it makes sense that it is denied.

he says the customer service of your insurance is really bad.

and that was good to contact the insurance commissioner.

this from my DH on drugs and chemo riding an exercise bike in a hospital room.