Chicken Wendy...
I don't know if you've thought of this...but surely there is a butcher shop close by, or some sort of game processor that you could maybe take him to and have the deed "done" rather than having you do it yourself?
I can't imagine them charging you if you didn't want to have the bird to eat.
While I don't agree with culling...I can CERTAINLY respect and understand your point, too...so I just want you to know you're doing what is right and best for your family...I guess...supporting you is what I should say...because you already know it is right and best.
I also commend you on the fact that you did not want to just hand your problem off to someone else...it appears that is probably why you got him on Craig's and his previous owner just kept "mum" about it.
I just had to re-home 2 of my roos...they are young and were fighting 'til the death. In my case, however, it was a territorial battle over 6 hens...so a re-home was possible, because to humans, they are the sweetest gentlemen you'd ever see.
I just rehomed because I didn't want more blood-shed, as well as the possibility that my children could accidentally "challenge" their roo-ness...and get spurred.
I got spurred once with "growing spurs" from my roo, Billy...man, that hurt! I can only imagine what would happen with "full on" spurs.