(and I'm talking from experience here).
With all due respect I really don't see any indications that you are. It's quite easy to envision a scenario where they don't want to reveal exactly how they determined the player was multi-accounting, because if they did then scammers would realize "Oh, they look for those kind of things, I'll have to do something else."
The KYC ID process is likely tied into this, but there's a small chance that its not. I think it would be great if Sportsbet wanted to expand on their findings and clarify the situation here, but even if they don't, I'm not going to be supporting any flags against them based on this issue.
In the real world this is how you loose market shares/customers.
They do hundreds of millions of dollars of business every year and have been at it for four years -- they are as "real world" as they come. Their business isn't exactly hurting, either.
So just imagine a moment their "black box" or "secret sauce" or however you call it tags you falsely for multi accounting, and gives them ground to refuses payment of a few thousand bucks, wouldn't you want a chance to defend yourself on the matter in a civilized manner?
Of course, and they did. In my very first post on this issue I mentioned that perhaps it was a false positive and that no sportsbook is perfect in that regard. However, what it boils down to is
we don't really know one way or the other, and if you want to just take a newbie account's word over theirs on the issue, well, that's up to you. Just don't expect others to follow suit. If suddenly a bunch of similar complaints started appearing in the future, perhaps I'd be more inclined to think otherwise.