We know from discussion elsewhere in the story that "photoids" are considered to use at least a solar system's worth of energy. In the passage you cite we learn the "two-vector foil" uses even more (which makes sense given the fantastical nature of this attack). ISTM the party who has "easy" access to an armory of these doomsday devices will have to wait a really long time for a good reason to fear the party who is still stuck in orbit around a single star.

Liu does lampshade the idea that performing such high-energy attacks should itself be a giant "here is a dangerous enemy" signal, but does so just to write it off as something that never happens. At the very least, frugal genocidal galactic civilizations should probably leave it to other genocidal galactic civilizations to actually do the tremendously expensive genociding. Given the eagerness we see in this passage, it can't be uncommon for multiple attacks to be launched by different parties simultaneously!

It's a great trilogy, and I'm glad Netflix are going to do something with it. (I really hope they don't whitewash the casting like many other productions. The fact that most characters are Chinese is important to the story.) This particular aspect just stood out to me.