Haha good timing, I just read that article and then popped over here
The contest organizing body seems to be in the belief that this behaviour is okay - personally, I haven't much of a stance on this topic, but it's an interesting debate. If the insect is truly flying away perfectly fine afterwards, is any real harm done? Do the insects feel that they're "drugged" - ie, are they sentient to some extent? (Draws a parallel here to recent events in the UK re crustaceans.)
If these insects do not have a conscious of any sort - is it then okay to drug or even kill them? If not, then is it okay to cut flowers and such for a photo? How about invasive insects or pests? Lots of hard questions that lead you down a rabbit hole of thought...