That responce is so bogus, they are 100% responcible for common building factors that make a plane air worthy .that would include, the firewall, the servo mounting plates , the wing joiners and mouting mechanisum and tail and fin substrcutures. This is getting to the point that manufactures will have lawsuits if they dont simply take care of basics. I dont mean working gear , or luxuarys that can all have problems , I mean basic construction that keeps models safe and fun . If they dont step up the AMA will be faced with liability claims that will kill this hobby . I went thru this with the H9 corsair, the plane is great but I reinforced the firewall based on post that I had read on RCU. If not I would have bet the firewall woudl have pulled off just like the one posted .
Good luck but this is one case that i feel you are correct , you did not build the kit you bought it with the assumption that the basic structure was airworthy and safe .That failure could have caused a seriuos injury .