Head on impact would not cause cracks close to the neutral axis of the tube and along the length of the tube, it would most likely cause rippling under the DT and/or cracking of the top of the top tube in the HAZ of the weld or the weld itself.
A hard landing would cause the opposite of this. Cracks behind (or in) the underside of the DT weld across the tube.
I have 30 years of experience as a qualified mechanical engineer designing bikes for hard riding, and I would warranty this frame without question.
Giving the OP a hard time based on photos that are at an angle which really doesn't allow you to judge the fork angle is unreasonable.
A hard landing would cause the opposite of this. Cracks behind (or in) the underside of the DT weld across the tube.
I have 30 years of experience as a qualified mechanical engineer designing bikes for hard riding, and I would warranty this frame without question.
Giving the OP a hard time based on photos that are at an angle which really doesn't allow you to judge the fork angle is unreasonable.