Traffic from an HN link is a lot over the course of a few hours, but it isn't that hard to handle. A single dedicated server usually won't even break a sweat. That's why this looks really bad.
What do you want for free? "A single dedicated server" costs something... this guy is almost certainly running on the free quota.
I don't think this looks bad for Google -- it looks bad for the author. The fact that he's using the freebie *.appspot.com rather than a dedicated domain gives you some indication of his dedication to the project.
A single server not breaking a sweat means that this can be handled by a middling VPS that is breaking a sweat, and that load only lasts a few hours. That means that it's stupidly cheap for Google to provide for a few hours of load like this, and the ability to absorb a huge spike on a cheapo plan is supposed to be one of the main points of cloud hosting.
Lots of people make cool stuff without dotting all the i's. That doesn't look bad on them - it just means they're doing the hard stuff and skipping the grungy parts of a project until it seems necessary.
