Sport tires are simply too grippy for a tandem lobby, but they are driftable, it all depends on power, setup, tire size etc.
Hell, I can drift racing softs but it doesn't mean I should. In my opinion comfort hards or mediums are optimal for tandem drifting. The way I see it is, comfort hards are like a budget, low quality tire. They're great for beginners as they practically slide themselves, but even seasoned drifters still use them. Here's why.
Edit, accidentally posted before I was finished. The reason why most people see CH as the "proper" tire is that there's a stigma associated with all the other compounds. If you don't use CH, you aren't "pro", or "can't tandem", really though I see comfort mediums as the tire that most closely resembles the majority of real life drift tires. Just from looking at the way cars react to weight shifting on Youtube will quickly prove that their cars react nothing like a GT5 drift car on CH.
I see CS as more of a professional level tire, close to what a D1 or Formula D driver would use, and the difference in speed between them and CH is too great for consistent tandems.
I don't know, I'm pretty much ranting, but from my experiences comfort medium tires are the most realistic tire in terms of how most real life drift cars perform.
If people want to drift sports, go for it, but don't expect to tandem consistently with a CH or CM user, the difference in speed and grip is too great. For solo drifting I guess its fine.