Going off of pure mathematics and ideal scenario/recognition, Kitana's D1 can be punished on reaction. Below is the math and explanation:
D1 Start-Up is 6 frames. We don't have active frames to my knowledge, so I'll assume 2, then Kitana is -15. That's a total 23 frames. To really drive this home, if you are godlike and beginning having your reaction on frame 1 of Kitana's D1, it's a 23 frame reaction.
Almost all fighting games (save some weird examples) run at 60 frames per second. Milliseconds are exactly what it sounds like and there are 1,000 of them in a single second. With that, if you take 1,000 (milliseconds)/60 (frames), you'll find that each frame in a fighting game represents 16.67 milliseconds.
So, if we look at the 23 frame perfect reaction to a Kitana D1, and view it in milliseconds, it's 383ms. Keep in mind that this is the last possible moment a punish would connect, at 384ms, Kitana would block, therefore it not being punished.
Now, the most important thing is the startup on the punishing move. 6 being the fastest startup in the game (Smoke D1 counterpoke), with 9 being more like a full combo punish startup move (Smoke 21xSB punish). This gets us to whether it can be punished, here's that info:
D1 Counterpoke - 23 Frame Rection on Kitana D1 = 383ms, but in order to connect that attack we would need to have started the D1 counterpoke earlier in order for it to punish. At 6 frames, we would need to start the punish 100ms sooner, in order for the 1st active frame of Smoke's D1 to contact Kitana at 383ms, so that's 283ms to react.
21xSB Punish - 23 Frame Rection on Kitana D1 = 383ms, but in order to connect that attack we would need to have started the 21xSB earlier in order for it to punish. At 9 frames, we would need to start the punish 150ms sooner, in order for the 1st active frame of Smoke's 2 to contact Kitana at 383ms, so that's 233ms to react.
So, in summary, punishing Kitana's D1 with a Smoke D1 would give you 283ms to react and punishing with 21xSB would give you 233ms to react. Now that we have that, we need human reaction time, which we'll use the following site for info:
http://www.humanbenchmark.com/tests/reactiontime/statistics
We can see here the average reaction time is around 250ms. Things to keep in mind about this website and these results:
1) People are staring at a bright red box waiting for it to turn bright green. Recognition here is insanely easy and expected as you are taking a reaction test.
2) The argument in this thread is 100% reacting and punishing--people taking this test can anticipate and click early (failing) until they get it right to lower their results.
With that said, if this thread is about dick swinging, carry on, but if it's not, take the test 10 times. If you prematurely click any of the 10 test sets, disregard the result. Take your average of your 10 tests that were 100% non-premature clicks and average your results.
Even if your results come out to <233ms, it's still a bright red box turning green, which is obvious when compared to identifying an animation in a fighting game.
Kitana D1s get punished in the same way that throws get teched--there is contextual information being used to anticipate the occurrence so an ideal reaction can be had. 100% punishing a blocked D1, no matter how random it is, I think is almost impossible. Again, the key here being 100% reaction, not I punish it sometimes. Also, the move used to punish is a huge factor as the quicker the startup, the more time you have to react and press the button.
TLDR: Human reaction 100% of the time to a blocked Kitana D1, while technically possible, is highly unlikely without anticipation/context information. This is where mixups come into play and can hinder you from reacting frame perfect 1 on the D1.