Don't think it's off topic to make sure we're honoring the rules of the site. There's a good reason they don't want us to use group buy sites here and I'd like to know if I'm being directed to one so I can decide for myself.
I've done a little research on TOM aka Whitehawk Ventures. They're definitely a "flash sale" site, but not all flash sale sites are group buy sites. If they haven't announced that they're a group buy sites, we can't assume they are based on nothing other than that they're a flash sale site. Some flash sale sites like Woot will just buy a pile of unsold crap super cheap and then resell it regular cheap.
However, there are anecdotal reports that TOM "negotiates pricing" with their suppliers, and that the shipping takes a while. Both of these are red flags that they're not just pre-buying a bunch of crap, but rather they're getting commitments to buy first and then getting the product after. That's pretty much a group buy scenario.
So no, while there's no solid proof one way or the other, it's very likely that it's a group buy site. Feel free to make your own decision on what you believe and whether or not you'd like to support them.
EDIT - Direct from their FAQ: "Part of the reason why ToMo has such low prices is that we don’t carry any inventory of our products. We pass the warehouse cost savings onto you so that you can enjoy the best prices available. We also negotiate with our vendors to ensure that their products are seen by people who appreciate good design, high quality and great value, and in return, they give us exceptional pricing."