Know When to Talk's R states:
R commit: After you block your opponent's attack, each player adds the top card of their deck to their card pool face down. You may not play an attack as a Reversal to this attack.
and Demuth's Sponsorship's R states:
R commit: After an attack that you completely block resolves, reveal the top card of your deck. If it is an attack, play it as a Reversal (no control check necessary). Otherwise, add that card to your momentum. You may only play one copy of this ability per attack.
Now since Demuth's Sponsorship doesn't provide the actual Reversal ability, rather creates a situation where the Reversal ability can be used, I can still respond with Demuth's Sponsorship after Know When to Talk has been activated right? All that will happen is that if I reveal an attack with Demuth's then it goes back to the top of my deck instead of being played as a Reversal. Correct?