They were only prepared for dismal sales. They said the server initially ran 'less well' with 10s of thousands of people online at once. They sold 18,000 copies. All of those people will want to be online at once at the start, so they weren't even really prepared for the real sales they got.
Saying they were only prepared for "dismal sales" is a bit misleading. They expected that the initial launch wouldn't have a huge number of people—it is an independently published game in a niche market with almost no advertising budget, after all—but that the numbers would continue to grow as word-of-mouth spread. This would've given them plenty of time to worry about scaling issues as they started to appear.
It's true that this scaling would've needed to happen eventually if the game took off, but there's no disputing that the launch has suffered a bit from the unexpected popularity. If they were all paying customers, that would be one thing; however, as it stands, the developers had to go out of their way to support a bunch of freeloaders and deal with criticism saying they're unprepared for a launch. It's a pretty rotten way to treat a company that's been very customer-friendly and supportive in the past.
Not only that, they also have to put up with these absurd justifications. "The website didn't tell me enough, I don't trust reviews, and there's no demo—piracy is my only option!" "The pirates helped them identify their scaling issues!" "If only they'd had a serial code then we would've respected their rights!"
I don't mean to single you out—the first quote there isn't even something you said—but we really don't need more people trying to spin piracy as "not so bad" or whatever. 100,000 people are assholes who probably weren't customers anyways, and there is no romantic "sticking it to the man" tale to be had here. I hope that this doesn't discourage Stardock and Gas Powered Games from making PC games in the future.