Regardless of the cause of the lean, if a tree like that was in danger of hitting my house I’d drop it like a hot rock.
Sounds like you paid a reasonable amount and like the other posters in this thread I agree it needed to come down.
So well done, fella!
And if those roots aren’t all rotted youre looking at underground root flare that for white oaks is ~4x the diameter of the base of the stump (enormous if the tree were to fall over and pull all that up) so… sounds like you got a good price for him to limb it fell it and grind that stump. And that it was the right call!