There's no notice whatsoever on their site to let you know that they aren't yet functional on the 6.7 update.
Out of curiosity Ed, what method would you prefer?
I'm a very slow and cautious guy with my production shop - we check and check and check and double check before we make changes, because backups are the one thing that just have to work no matter what. In my mind, backups should be like a screwdriver or a hammer - you don't necessarily do anything fancy with them, but when you pick them up and turn/hit, they work, because that's all they do.
So when there's an update announced from VMware or Microsoft, I wait until there is published documentation from Veeam (and our few other side products) until we touch anything. Why mess with what isn't broken? For me, the platform support page is the authoritative document that tells me whether or not I should even be thinking about updating, not whether I will or not. But if that's not what works for you, what would be the best method to tell you "Hey, 6.x is released, we're not ready yet for it." As an IT provider, I know that's what I'd be asking if I were in Gostev's shoes.
As a customer, I see VMware updates (and for our small Hyper V cluster, Microsoft updates), as threats. Hearing that the partners for VMware don't get GA code until public release is absolutely absurd in my mind (directed @ VMware, not Veeam), and for me it's one of those things where VMware and Microsoft have to prove first in public, non-lab settings that their stuff works before I'm ready to commit. We're a medium sized shop, but we don't have the space for the necessary redundancy on some of our biggest servers, so we're heavily reliant on our backups in case "it" hits the fan. I would never dream of a Day1 update, much less pushing it to my production servers.
I know, hindsight is 20/20 here, and if I were in your position, I'd be a mixture of furious and beating myself up in between glasses of scotch. But really, I wouldn't know where else to put the blame but me.