I've no idea their internal decision on metrics for the test, but they did shoot down something in a pretty low orbit. It was at about 300km. The ISS orbits at 400km. "Space" begins at around 100km. Shooting low is exactly what you want to do to minimize risk since it means the pieces will enter the atmosphere more rapidly and harmlessly burn up. Like the article mentions only 24 pieces of trackable debris ended up in an orbit sufficiently high to possibly intercept the ISS. This is among the 23,000 other trackable pieces of debris including 3,000 from a Chinese satellite destruction test done with somewhat less regard, and about a million smaller pieces of various debris.

The article mentions the risk of any impact increased by 44% without giving the baseline. No idea what that is, but it's going to be some extremely low figure remaining an extremely low figure -- e.g. 0.001% becoming 0.00144%. And an "imminent" collision isn't imminent. The ISS has maneuvering thrusters, and in fact would gradually fall out of orbit without them! This [1] page shows the height of the ISS over time which is a convenient way of seeing how often it fires its maneuvering thrusters. Suffice to say, it's a very regular thing.

I think the bigger reason we're upset is because of the technology itself. As nations become more capable of independently defending themselves it chips away at America's martial dominance, which is a major source of our political clout.

[1] - https://www.heavens-above.com/IssHeight.aspx