A lot of thought has gone into this and other possible explanations. Isaac Arthur, of course, has an excellent video [1] on this issue. His entire library on the Fermi Paradox is worth watching.
The short version of why this seems unlikely is that there really is no hiding a K2 civilization for many reasons. For example, access to this much energy and having a megastructure as large as the Solar System (give or take) would allow you to create incredibly high resolution telescopes (with an without interferometry).
But consider this: if you, as a spacefaring civilization, want to be left alone, the best way to do it is to make sure nobody comes into your neighbourhood. If you "hide" that may happen accidentally. Isn't it better to advertise your presence and otherwise keep people away to avoid unintentional conflict?
This could also be due to the fact that the dark forest hypothesis is correct.
https://en.wikipedia.org/wiki/Dark_forest_hypothesis