...and what exactly would be wrong with that? Worst case scenario the BTA price goes to $10 assuming you're buyer 1001 and everyone else bought the $10 pack. You still get a heck of a deal.
In some cases, the processing took longer than a minute (e.g. PayPal), so they missed the window. The argument is that the buyer would not have otherwise paid $10 for the bundle if it didn't have Starbound. (to be fair, HB apparently has been offering refunds in this case)