This isn't completely true. You can soff on hboot 1.58. It's been done many times and I did it myself.
This guide is pretty straight forward and geared exactly toward your situation: http://forum.xda-developers.com/show....php?t=1889438
Otto, how's it going? , I know your situation sucked. It happens for some people, but it's not the case that everyone on 1.58 has to go through it. Most people can just go with juopunutbear s-off. It's usually when there's a phone repair and the motherboard had been swapped. It causes a mismatch in firmware with no option to run an ruu.
I recently walked another user through rooting their sprint 1.58 hboot with success with brick/downgrade, though unknownforce's ultimate.zip did not work for them