I was watching the Elvis cake challenge the other day and they had a really traditional judge on there. It wasn't KV... but she did not like the fact that Duff was using a blowtorch to heat up his icing and called the other judges to have a meeting about it. Then they deducted points for it!
Duff was so funny.. his response was simply, "I can't imagine life without a blow torch"
I think it was because he was actually pointing the torch at the icing, rather than just heating the bowl. She was pretty stodgy. She said 'it just isn't done that way'. However, pastry chefs use one all the time to carmelize sugar for brulee.
I think it just didn't really matter that much. I love Duff, and all his powertools.
I've seen that challenge, but I don't really remember the details. But yes it must have been because he put the torch directly on the icing rather than the bowl, because heating the bowl with the blowtorch is common practice (I was taught that way in culinary school! lol)