The 265 rear makes sense as to why the tires look "stretched" and the rear profile/thickness doesn't look as substantial as a 275 would. Also the fact that the are Falken 452s (I had the 451s and they had the stretch look. . I thought they supposedly fixed that sizing issue with the 452s, but I guess not).
Next time around I would recommend trying the Kumho SPTs in 215/35/18 and 275/30/19. They'll be much more squared up (no tire stretch) with the 18x8 fronts and 19x10 rears.
Goodyear actually makes the sizes he would need in the F1 GS D3 sizes. He can get a 225/35/18 and then a 275/35/19. I have the 225/35/18 on a 18/8.5 wheel and it fits great with no stretching.