Ran into similar lawyer bullshiite recently. Previous owner of my 4Runner had pu larger than stock tires on. Had a slow leak and asked Discount tire to fix when getting a new spare tire.
They would not touch it as it was on a rim 0.5” under spec for that tire size.
They were the dealer that had installed the tires several years earlier. I just wanted a freaking leak fixed, not mount a tire.
I used to have them do tire repairs and I would pay and give 'em a nice tip.
This last time, when they refused to repair my leak, I used what would have been their tip to buy a Slime Deluxe Tire Plug Kit and a bottle of Slime liquid sealant at Autozone. I plugged the place where a small screw had punctured the tire and put the sealant into the tire, then used their free compressed air to inflate the tire.
I have to go back there every two months to top off the pound of air pressure that tire loses with their air, but I never buy anything there anymore.