Wow, it’s amazing that it worked! I spent quite a while debating whether I needed to alter the source code to implement this modification to the ISM. Fortunately, simply configuring the property through the Utility Widget proved to be sufficient to get it functioning!
Below you can see a video showing the result + how I implemented the change.
EDIT: It seems to be functioning to some extent, as demonstrated in the video I’ve shared. However, there are limitations, such as the inability to select Packed Level Actors—once modified, they become entirely unselectable. Additionally, the modification isn’t retained; if you reload the level, the actor containing Instance Static Mesh Components reverts to being unselectable.