If you're not at least quite happy with the sales of your product, you don't report about it at all usually. We also know via Famitsu and Dengeki that the game sold at least 80% of its shipment first week.
They're being pretty open about their sales and that's perfectly fine, they're still a small dev/publisher so they don't have some kind of weird PR rules to follow unlike big companies which is pretty cool actually.
Once again there's nothing to see in that tweet other than them being informative, it's not negative nor is it positive.
Selling your shipment tells nothing about publisher expectations, only retailer expectations.
@encephalo: No, definitely above 10k