I appreciate you apologised for taking the needle off someone's record James (And if Rob did do it deliberatly to wind you up that was just as bad) but until proven otherwise you don't really know whether Rob has a legitimate copy of the acetate. As Ady said, it's just as likely for another acetate to turn up these days as it is for a vinyl copy of a really rare single.
I wouldn't make a habit of taking the needle off other people's records though because not only is it a very rude thing to do, it hasn't shown you in a good light at all, but I think think of quite a large number of DJs would would react quite violently to someone messing with their records, even if you did have Mick H there to hold your hand.
You should have shown you have some class rather than throwing your dummy out of the pram at the venue. A little story, many years ago, just after I had bought the Magnetics - I have a girl, I was booked to DJ somewhere quite local for me. The promoter who had booked me then proceded to do the spot before me and play a boot of the Magnetics. All I did was smile. It didn't make me any less of a person, or any less of a DJ just because someone else has to play a bootleg, but I never for one minute considered taking the needle off the record. Stop taking yourself too seriously and go out to enjoy yourself instead.
Dear me, DJs having tantrums, whatever next