According to Nick's book, Dave didn't sing it because he couldn't do it justice. It's the same reason the Floyd never played tracks off Animals after Roger left: Dave just couldn't muster up enough vitriol to sing them.

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what do you teach your children about me?
what do you teach your little children about me?
pimp, thug, bling drug lord of the undergrounded kings
how can you be so sure i won't call down the rain?
what do you teach your little children about me?
you point your gun, wait, hide and run. i see it plain