Definitely 'caused confusion, in particular:
A) @hafling's comment (11195956) now looks like it is directly referencing the parent discussion (therefore it's lost its context).
B) Your comment about detaching it (11196963) references the comment it was detached from, BUT because a link to a sub-thread opens the linked sub-thread as a parent thread, it appears to be a brand-spanking new thread (if I haven't properly articulated this, click https://news.ycombinator.com/item?id=11195895 and you'll get the idea)
C) I don't see any indication that the offtopic sub-thread has been marked as offtopic.
Combining these, B makes it look like the relevant conversation has been completely detached from the relevant conversation, while A and C makes it look like the off-topic conversation has been left, but it's now lost it's context.
I absolutely agree, the sub-thread is off-topic. But the detachment result is just downright confusing!
I'd rather there be a visible flag that a sub-thread is off-topic with a way to collapse the off-topic thread (something I'd love to see anyway for several other reasons), maybe even auto-collapse an off-topic thread (somewhat similarly to the way dead-threads default to not being shown, and when they are shown they are flagged as such).
Just my thoughts after being really confused! (Kinda ironic, given my original comment on the sub-thread - https://news.ycombinator.com/item?id=11196732)
@dang - Special thanks for helping me understand what was going on!
edited: trying to make my statement slightly more clear